diff --git a/examples/BASIC/BASIC.ino b/examples/BASIC/BASIC.ino
index 7a6e200..4099b71 100644
--- a/examples/BASIC/BASIC.ino
+++ b/examples/BASIC/BASIC.ino
@@ -236,7 +236,7 @@ void loop() {
 
 static void co2Update(void) {
   int value = ag.s8.getCo2();
-  if (value >= 0) {
+  if (utils::isValidCO2(value)) {
     measurements.CO2 = value;
     getCO2FailCount = 0;
     Serial.printf("CO2 (ppm): %d\r\n", measurements.CO2);
@@ -244,7 +244,7 @@ static void co2Update(void) {
     getCO2FailCount++;
     Serial.printf("Get CO2 failed: %d\r\n", getCO2FailCount);
     if (getCO2FailCount >= 3) {
-      measurements.CO2 = -1;
+      measurements.CO2 = utils::getInvalidCO2();
     }
   }
 }
@@ -519,10 +519,10 @@ static void updatePm(void) {
     pmFailCount++;
     Serial.printf("PMS read failed: %d\r\n", pmFailCount);
     if (pmFailCount >= 3) {
-      measurements.pm01_1 = -1;
-      measurements.pm25_1 = -1;
-      measurements.pm10_1 = -1;
-      measurements.pm03PCount_1 = -1;
+      measurements.pm01_1 = utils::getInvalidPMS();
+      measurements.pm25_1 = utils::getInvalidPMS();
+      measurements.pm10_1 = utils::getInvalidPMS();
+      measurements.pm03PCount_1 = utils::getInvalidPMS();
     }
   }
 }
@@ -567,5 +567,7 @@ static void tempHumUpdate(void) {
     }
   } else {
     Serial.println("SHT read failed");
+    measurements.Temperature = utils::getInvalidTemperature();
+    measurements.Humidity = utils::getInvalidHumidity();
   }
 }
diff --git a/examples/BASIC/OpenMetrics.cpp b/examples/BASIC/OpenMetrics.cpp
index 5270768..3392d97 100644
--- a/examples/BASIC/OpenMetrics.cpp
+++ b/examples/BASIC/OpenMetrics.cpp
@@ -65,14 +65,14 @@ String OpenMetrics::getPayload(void) {
     add_metric_point("", String(measure.CO2));
   }
 
-  float _temp = -1001;
-  float _hum = -1;
-  int pm01 = -1;
-  int pm25 = -1;
-  int pm10 = -1;
-  int pm03PCount = -1;
-  int atmpCompensated = -1;
-  int ahumCompensated = -1;
+  float _temp = utils::getInvalidTemperature();
+  float _hum = utils::getInvalidHumidity();
+  int pm01 = utils::getInvalidPMS();
+  int pm25 = utils::getInvalidPMS();
+  int pm10 = utils::getInvalidPMS();
+  int pm03PCount = utils::getInvalidPMS();
+  int atmpCompensated = utils::getInvalidTemperature();
+  int ahumCompensated = utils::getInvalidHumidity();
 
   if (config.hasSensorSHT) {
     _temp = measure.Temperature;
@@ -89,28 +89,28 @@ String OpenMetrics::getPayload(void) {
   }
 
   if (config.hasSensorPMS1) {
-    if (pm01 >= 0) {
+    if (utils::isValidPMS(pm01)) {
       add_metric("pm1",
                  "PM1.0 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm01));
     }
-    if (pm25 >= 0) {
+    if (utils::isValidPMS(pm25)) {
       add_metric("pm2d5",
                  "PM2.5 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm25));
     }
-    if (pm10 >= 0) {
+    if (utils::isValidPMS(pm10)) {
       add_metric("pm10",
                  "PM10 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm10));
     }
-    if (pm03PCount >= 0) {
+    if (utils::isValidPMS03Count(pm03PCount)) {
       add_metric("pm0d3",
                  "PM0.3 concentration as measured by the AirGradient PMS "
                  "sensor, in number of particules per 100 milliliters",
@@ -120,28 +120,28 @@ String OpenMetrics::getPayload(void) {
   }
 
   if (config.hasSensorSGP) {
-    if (measure.TVOC >= 0) {
+    if (utils::isValidVOC(measure.TVOC)) {
       add_metric("tvoc_index",
                  "The processed Total Volatile Organic Compounds (TVOC) index "
                  "as measured by the AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.TVOC));
     }
-    if (measure.TVOCRaw >= 0) {
+    if (utils::isValidVOC(measure.TVOCRaw)) {
       add_metric("tvoc_raw",
                  "The raw input value to the Total Volatile Organic Compounds "
                  "(TVOC) index as measured by the AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.TVOCRaw));
     }
-    if (measure.NOx >= 0) {
+    if (utils::isValidNOx(measure.NOx)) {
       add_metric("nox_index",
                  "The processed Nitrous Oxide (NOx) index as measured by the "
                  "AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.NOx));
     }
-    if (measure.NOxRaw >= 0) {
+    if (utils::isValidNOx(measure.NOxRaw)) {
       add_metric("nox_raw",
                  "The raw input value to the Nitrous Oxide (NOx) index as "
                  "measured by the AirGradient SGP sensor",
@@ -150,7 +150,7 @@ String OpenMetrics::getPayload(void) {
     }
   }
 
-  if (_temp > -1001) {
+  if (utils::isValidTemperature(_temp)) {
     add_metric(
         "temperature",
         "The ambient temperature as measured by the AirGradient SHT / PMS "
@@ -158,7 +158,7 @@ String OpenMetrics::getPayload(void) {
         "gauge", "celsius");
     add_metric_point("", String(_temp));
   }
-  if (atmpCompensated > -1001) {
+  if (utils::isValidTemperature(atmpCompensated)) {
     add_metric("temperature_compensated",
                "The compensated ambient temperature as measured by the "
                "AirGradient SHT / PMS "
@@ -166,14 +166,14 @@ String OpenMetrics::getPayload(void) {
                "gauge", "celsius");
     add_metric_point("", String(atmpCompensated));
   }
-  if (_hum >= 0) {
+  if (utils::isValidHumidity(_hum)) {
     add_metric(
         "humidity",
         "The relative humidity as measured by the AirGradient SHT sensor",
         "gauge", "percent");
     add_metric_point("", String(_hum));
   }
-  if (ahumCompensated >= 0) {
+  if (utils::isValidHumidity(ahumCompensated)) {
     add_metric("humidity_compensated",
                "The compensated relative humidity as measured by the "
                "AirGradient SHT / PMS sensor",
diff --git a/examples/DiyProIndoorV3_3/DiyProIndoorV3_3.ino b/examples/DiyProIndoorV3_3/DiyProIndoorV3_3.ino
index 295a2ca..df059b7 100644
--- a/examples/DiyProIndoorV3_3/DiyProIndoorV3_3.ino
+++ b/examples/DiyProIndoorV3_3/DiyProIndoorV3_3.ino
@@ -234,7 +234,7 @@ void loop() {
 
 static void co2Update(void) {
   int value = ag.s8.getCo2();
-  if (value >= 0) {
+  if (utils::isValidCO2(value)) {
     measurements.CO2 = value;
     getCO2FailCount = 0;
     Serial.printf("CO2 (ppm): %d\r\n", measurements.CO2);
@@ -242,7 +242,7 @@ static void co2Update(void) {
     getCO2FailCount++;
     Serial.printf("Get CO2 failed: %d\r\n", getCO2FailCount);
     if (getCO2FailCount >= 3) {
-      measurements.CO2 = -1;
+      measurements.CO2 = utils::getInvalidCO2();
     }
   }
 }
@@ -571,10 +571,10 @@ static void updatePm(void) {
     pmFailCount++;
     Serial.printf("PMS read failed: %d\r\n", pmFailCount);
     if (pmFailCount >= 3) {
-      measurements.pm01_1 = -1;
-      measurements.pm25_1 = -1;
-      measurements.pm10_1 = -1;
-      measurements.pm03PCount_1 = -1;
+      measurements.pm01_1 = utils::getInvalidPMS();
+      measurements.pm25_1 = utils::getInvalidPMS();
+      measurements.pm10_1 = utils::getInvalidPMS();
+      measurements.pm03PCount_1 = utils::getInvalidPMS();
     }
   }
 }
@@ -619,5 +619,7 @@ static void tempHumUpdate(void) {
     }
   } else {
     Serial.println("SHT read failed");
+    measurements.Temperature = utils::getInvalidTemperature();
+    measurements.Humidity = utils::getInvalidHumidity();
   }
 }
diff --git a/examples/DiyProIndoorV3_3/OpenMetrics.cpp b/examples/DiyProIndoorV3_3/OpenMetrics.cpp
index 5270768..3392d97 100644
--- a/examples/DiyProIndoorV3_3/OpenMetrics.cpp
+++ b/examples/DiyProIndoorV3_3/OpenMetrics.cpp
@@ -65,14 +65,14 @@ String OpenMetrics::getPayload(void) {
     add_metric_point("", String(measure.CO2));
   }
 
-  float _temp = -1001;
-  float _hum = -1;
-  int pm01 = -1;
-  int pm25 = -1;
-  int pm10 = -1;
-  int pm03PCount = -1;
-  int atmpCompensated = -1;
-  int ahumCompensated = -1;
+  float _temp = utils::getInvalidTemperature();
+  float _hum = utils::getInvalidHumidity();
+  int pm01 = utils::getInvalidPMS();
+  int pm25 = utils::getInvalidPMS();
+  int pm10 = utils::getInvalidPMS();
+  int pm03PCount = utils::getInvalidPMS();
+  int atmpCompensated = utils::getInvalidTemperature();
+  int ahumCompensated = utils::getInvalidHumidity();
 
   if (config.hasSensorSHT) {
     _temp = measure.Temperature;
@@ -89,28 +89,28 @@ String OpenMetrics::getPayload(void) {
   }
 
   if (config.hasSensorPMS1) {
-    if (pm01 >= 0) {
+    if (utils::isValidPMS(pm01)) {
       add_metric("pm1",
                  "PM1.0 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm01));
     }
-    if (pm25 >= 0) {
+    if (utils::isValidPMS(pm25)) {
       add_metric("pm2d5",
                  "PM2.5 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm25));
     }
-    if (pm10 >= 0) {
+    if (utils::isValidPMS(pm10)) {
       add_metric("pm10",
                  "PM10 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm10));
     }
-    if (pm03PCount >= 0) {
+    if (utils::isValidPMS03Count(pm03PCount)) {
       add_metric("pm0d3",
                  "PM0.3 concentration as measured by the AirGradient PMS "
                  "sensor, in number of particules per 100 milliliters",
@@ -120,28 +120,28 @@ String OpenMetrics::getPayload(void) {
   }
 
   if (config.hasSensorSGP) {
-    if (measure.TVOC >= 0) {
+    if (utils::isValidVOC(measure.TVOC)) {
       add_metric("tvoc_index",
                  "The processed Total Volatile Organic Compounds (TVOC) index "
                  "as measured by the AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.TVOC));
     }
-    if (measure.TVOCRaw >= 0) {
+    if (utils::isValidVOC(measure.TVOCRaw)) {
       add_metric("tvoc_raw",
                  "The raw input value to the Total Volatile Organic Compounds "
                  "(TVOC) index as measured by the AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.TVOCRaw));
     }
-    if (measure.NOx >= 0) {
+    if (utils::isValidNOx(measure.NOx)) {
       add_metric("nox_index",
                  "The processed Nitrous Oxide (NOx) index as measured by the "
                  "AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.NOx));
     }
-    if (measure.NOxRaw >= 0) {
+    if (utils::isValidNOx(measure.NOxRaw)) {
       add_metric("nox_raw",
                  "The raw input value to the Nitrous Oxide (NOx) index as "
                  "measured by the AirGradient SGP sensor",
@@ -150,7 +150,7 @@ String OpenMetrics::getPayload(void) {
     }
   }
 
-  if (_temp > -1001) {
+  if (utils::isValidTemperature(_temp)) {
     add_metric(
         "temperature",
         "The ambient temperature as measured by the AirGradient SHT / PMS "
@@ -158,7 +158,7 @@ String OpenMetrics::getPayload(void) {
         "gauge", "celsius");
     add_metric_point("", String(_temp));
   }
-  if (atmpCompensated > -1001) {
+  if (utils::isValidTemperature(atmpCompensated)) {
     add_metric("temperature_compensated",
                "The compensated ambient temperature as measured by the "
                "AirGradient SHT / PMS "
@@ -166,14 +166,14 @@ String OpenMetrics::getPayload(void) {
                "gauge", "celsius");
     add_metric_point("", String(atmpCompensated));
   }
-  if (_hum >= 0) {
+  if (utils::isValidHumidity(_hum)) {
     add_metric(
         "humidity",
         "The relative humidity as measured by the AirGradient SHT sensor",
         "gauge", "percent");
     add_metric_point("", String(_hum));
   }
-  if (ahumCompensated >= 0) {
+  if (utils::isValidHumidity(ahumCompensated)) {
     add_metric("humidity_compensated",
                "The compensated relative humidity as measured by the "
                "AirGradient SHT / PMS sensor",
diff --git a/examples/DiyProIndoorV4_2/DiyProIndoorV4_2.ino b/examples/DiyProIndoorV4_2/DiyProIndoorV4_2.ino
index c158856..20be418 100644
--- a/examples/DiyProIndoorV4_2/DiyProIndoorV4_2.ino
+++ b/examples/DiyProIndoorV4_2/DiyProIndoorV4_2.ino
@@ -261,7 +261,7 @@ void loop() {
 
 static void co2Update(void) {
   int value = ag.s8.getCo2();
-  if (value >= 0) {
+  if (utils::isValidCO2(value)) {
     measurements.CO2 = value;
     getCO2FailCount = 0;
     Serial.printf("CO2 (ppm): %d\r\n", measurements.CO2);
@@ -269,7 +269,7 @@ static void co2Update(void) {
     getCO2FailCount++;
     Serial.printf("Get CO2 failed: %d\r\n", getCO2FailCount);
     if (getCO2FailCount >= 3) {
-      measurements.CO2 = -1;
+      measurements.CO2 = utils::getInvalidCO2();
     }
   }
 }
@@ -614,10 +614,10 @@ static void updatePm(void) {
     pmFailCount++;
     Serial.printf("PMS read failed: %d\r\n", pmFailCount);
     if (pmFailCount >= 3) {
-      measurements.pm01_1 = -1;
-      measurements.pm25_1 = -1;
-      measurements.pm10_1 = -1;
-      measurements.pm03PCount_1 = -1;
+      measurements.pm01_1 = utils::getInvalidPMS();
+      measurements.pm25_1 = utils::getInvalidPMS();
+      measurements.pm10_1 = utils::getInvalidPMS();
+      measurements.pm03PCount_1 = utils::getInvalidPMS();
     }
   }
 }
@@ -662,5 +662,7 @@ static void tempHumUpdate(void) {
     }
   } else {
     Serial.println("SHT read failed");
+    measurements.Temperature = utils::getInvalidTemperature();
+    measurements.Humidity = utils::getInvalidHumidity();
   }
 }
diff --git a/examples/DiyProIndoorV4_2/OpenMetrics.cpp b/examples/DiyProIndoorV4_2/OpenMetrics.cpp
index 5270768..3392d97 100644
--- a/examples/DiyProIndoorV4_2/OpenMetrics.cpp
+++ b/examples/DiyProIndoorV4_2/OpenMetrics.cpp
@@ -65,14 +65,14 @@ String OpenMetrics::getPayload(void) {
     add_metric_point("", String(measure.CO2));
   }
 
-  float _temp = -1001;
-  float _hum = -1;
-  int pm01 = -1;
-  int pm25 = -1;
-  int pm10 = -1;
-  int pm03PCount = -1;
-  int atmpCompensated = -1;
-  int ahumCompensated = -1;
+  float _temp = utils::getInvalidTemperature();
+  float _hum = utils::getInvalidHumidity();
+  int pm01 = utils::getInvalidPMS();
+  int pm25 = utils::getInvalidPMS();
+  int pm10 = utils::getInvalidPMS();
+  int pm03PCount = utils::getInvalidPMS();
+  int atmpCompensated = utils::getInvalidTemperature();
+  int ahumCompensated = utils::getInvalidHumidity();
 
   if (config.hasSensorSHT) {
     _temp = measure.Temperature;
@@ -89,28 +89,28 @@ String OpenMetrics::getPayload(void) {
   }
 
   if (config.hasSensorPMS1) {
-    if (pm01 >= 0) {
+    if (utils::isValidPMS(pm01)) {
       add_metric("pm1",
                  "PM1.0 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm01));
     }
-    if (pm25 >= 0) {
+    if (utils::isValidPMS(pm25)) {
       add_metric("pm2d5",
                  "PM2.5 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm25));
     }
-    if (pm10 >= 0) {
+    if (utils::isValidPMS(pm10)) {
       add_metric("pm10",
                  "PM10 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm10));
     }
-    if (pm03PCount >= 0) {
+    if (utils::isValidPMS03Count(pm03PCount)) {
       add_metric("pm0d3",
                  "PM0.3 concentration as measured by the AirGradient PMS "
                  "sensor, in number of particules per 100 milliliters",
@@ -120,28 +120,28 @@ String OpenMetrics::getPayload(void) {
   }
 
   if (config.hasSensorSGP) {
-    if (measure.TVOC >= 0) {
+    if (utils::isValidVOC(measure.TVOC)) {
       add_metric("tvoc_index",
                  "The processed Total Volatile Organic Compounds (TVOC) index "
                  "as measured by the AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.TVOC));
     }
-    if (measure.TVOCRaw >= 0) {
+    if (utils::isValidVOC(measure.TVOCRaw)) {
       add_metric("tvoc_raw",
                  "The raw input value to the Total Volatile Organic Compounds "
                  "(TVOC) index as measured by the AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.TVOCRaw));
     }
-    if (measure.NOx >= 0) {
+    if (utils::isValidNOx(measure.NOx)) {
       add_metric("nox_index",
                  "The processed Nitrous Oxide (NOx) index as measured by the "
                  "AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.NOx));
     }
-    if (measure.NOxRaw >= 0) {
+    if (utils::isValidNOx(measure.NOxRaw)) {
       add_metric("nox_raw",
                  "The raw input value to the Nitrous Oxide (NOx) index as "
                  "measured by the AirGradient SGP sensor",
@@ -150,7 +150,7 @@ String OpenMetrics::getPayload(void) {
     }
   }
 
-  if (_temp > -1001) {
+  if (utils::isValidTemperature(_temp)) {
     add_metric(
         "temperature",
         "The ambient temperature as measured by the AirGradient SHT / PMS "
@@ -158,7 +158,7 @@ String OpenMetrics::getPayload(void) {
         "gauge", "celsius");
     add_metric_point("", String(_temp));
   }
-  if (atmpCompensated > -1001) {
+  if (utils::isValidTemperature(atmpCompensated)) {
     add_metric("temperature_compensated",
                "The compensated ambient temperature as measured by the "
                "AirGradient SHT / PMS "
@@ -166,14 +166,14 @@ String OpenMetrics::getPayload(void) {
                "gauge", "celsius");
     add_metric_point("", String(atmpCompensated));
   }
-  if (_hum >= 0) {
+  if (utils::isValidHumidity(_hum)) {
     add_metric(
         "humidity",
         "The relative humidity as measured by the AirGradient SHT sensor",
         "gauge", "percent");
     add_metric_point("", String(_hum));
   }
-  if (ahumCompensated >= 0) {
+  if (utils::isValidHumidity(ahumCompensated)) {
     add_metric("humidity_compensated",
                "The compensated relative humidity as measured by the "
                "AirGradient SHT / PMS sensor",
diff --git a/examples/OneOpenAir/OneOpenAir.ino b/examples/OneOpenAir/OneOpenAir.ino
index 81afb84..978c345 100644
--- a/examples/OneOpenAir/OneOpenAir.ino
+++ b/examples/OneOpenAir/OneOpenAir.ino
@@ -320,7 +320,7 @@ void loop() {
 
 static void co2Update(void) {
   int value = ag->s8.getCo2();
-  if (value >= 0) {
+  if (utils::isValidCO2(value)) {
     measurements.CO2 = value;
     getCO2FailCount = 0;
     Serial.printf("CO2 (ppm): %d\r\n", measurements.CO2);
@@ -328,7 +328,7 @@ static void co2Update(void) {
     getCO2FailCount++;
     Serial.printf("Get CO2 failed: %d\r\n", getCO2FailCount);
     if (getCO2FailCount >= 3) {
-      measurements.CO2 = -1;
+      measurements.CO2 = utils::getInvalidCO2();
     }
   }
 }
@@ -424,12 +424,8 @@ static void factoryConfigReset(void) {
             }
 
             /** Reset WIFI */
-            WiFi.enableSTA(true); // Incase offline mode
-            WiFi.disconnect(true, true);
-            if (ag->isOne() == false) {
-              WiFi.begin("airgradient", "cleanair");
-              Serial.println("Set WiFi connect to \"airgradient\"");
-            }
+            Serial.println("Set wifi connect to 'airgradient' as default");
+            WiFi.begin("airgradient", "cleanair");
 
             /** Reset local config */
             configuration.reset();
@@ -1027,10 +1023,10 @@ static void updatePm(void) {
       pmFailCount++;
       Serial.printf("PMS read failed: %d\r\n", pmFailCount);
       if (pmFailCount >= 3) {
-        measurements.pm01_1 = -1;
-        measurements.pm25_1 = -1;
-        measurements.pm10_1 = -1;
-        measurements.pm03PCount_1 = -1;
+        measurements.pm01_1 = utils::getInvalidPMS();
+        measurements.pm25_1 = utils::getInvalidPMS();
+        measurements.pm10_1 = utils::getInvalidPMS();
+        measurements.pm03PCount_1 = utils::getInvalidPMS();
       }
     }
   } else {
@@ -1058,12 +1054,12 @@ static void updatePm(void) {
       Serial.printf("[1] Relative Humidity compensated: %f\r\n",
                     ag->pms5003t_1.humidityCompensated(measurements.hum_1));
     } else {
-      measurements.pm01_1 = -1;
-      measurements.pm25_1 = -1;
-      measurements.pm10_1 = -1;
-      measurements.pm03PCount_1 = -1;
-      measurements.temp_1 = -1001;
-      measurements.hum_1 = -1;
+      measurements.pm01_1 = utils::getInvalidPMS();
+      measurements.pm25_1 = utils::getInvalidPMS();
+      measurements.pm10_1 = utils::getInvalidPMS();
+      measurements.pm03PCount_1 = utils::getInvalidPMS();
+      measurements.temp_1 = utils::getInvalidTemperature();
+      measurements.hum_1 = utils::getInvalidHumidity();
     }
 
     if (configuration.hasSensorPMS2 && (ag->pms5003t_2.isFailed() == false)) {
@@ -1088,12 +1084,12 @@ static void updatePm(void) {
       Serial.printf("[2] Relative Humidity compensated: %d\r\n",
                     ag->pms5003t_1.humidityCompensated(measurements.hum_2));
     } else {
-      measurements.pm01_2 = -1;
-      measurements.pm25_2 = -1;
-      measurements.pm10_2 = -1;
-      measurements.pm03PCount_2 = -1;
-      measurements.temp_2 = -1001;
-      measurements.hum_2 = -1;
+      measurements.pm01_2 = utils::getInvalidPMS();
+      measurements.pm25_2 = utils::getInvalidPMS();
+      measurements.pm10_2 = utils::getInvalidPMS();
+      measurements.pm03PCount_2 = utils::getInvalidPMS();
+      measurements.temp_2 = utils::getInvalidTemperature();
+      measurements.hum_2 = utils::getInvalidHumidity();
     }
 
     if (configuration.hasSensorPMS1 && configuration.hasSensorPMS2 &&
@@ -1233,6 +1229,8 @@ static void tempHumUpdate(void) {
                                                    measurements.Humidity);
     }
   } else {
+    measurements.Temperature = utils::getInvalidTemperature();
+    measurements.Humidity = utils::getInvalidHumidity();
     Serial.println("SHT read failed");
   }
 }
diff --git a/examples/OneOpenAir/OpenMetrics.cpp b/examples/OneOpenAir/OpenMetrics.cpp
index 0f4c92c..c458a8c 100644
--- a/examples/OneOpenAir/OpenMetrics.cpp
+++ b/examples/OneOpenAir/OpenMetrics.cpp
@@ -65,14 +65,14 @@ String OpenMetrics::getPayload(void) {
     add_metric_point("", String(measure.CO2));
   }
 
-  float _temp = -1001;
-  float _hum = -1;
-  int pm01 = -1;
-  int pm25 = -1;
-  int pm10 = -1;
-  int pm03PCount = -1;
-  int atmpCompensated = -1;
-  int ahumCompensated = -1;
+  float _temp = utils::getInvalidTemperature();
+  float _hum = utils::getInvalidHumidity();
+  int pm01 = utils::getInvalidPMS();
+  int pm25 = utils::getInvalidPMS();
+  int pm10 = utils::getInvalidPMS();
+  int pm03PCount = utils::getInvalidPMS();
+  int atmpCompensated = utils::getInvalidTemperature();
+  int ahumCompensated = utils::getInvalidHumidity();
   if (config.hasSensorPMS1 && config.hasSensorPMS2) {
     _temp = (measure.temp_1 + measure.temp_2) / 2.0f;
     _hum = (measure.hum_1 + measure.hum_2) / 2.0f;
@@ -123,28 +123,28 @@ String OpenMetrics::getPayload(void) {
   }
 
   if (config.hasSensorPMS1 || config.hasSensorPMS2) {
-    if (pm01 >= 0) {
+    if (utils::isValidPMS(pm01)) {
       add_metric("pm1",
                  "PM1.0 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm01));
     }
-    if (pm25 >= 0) {
+    if (utils::isValidPMS(pm25)) {
       add_metric("pm2d5",
                  "PM2.5 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm25));
     }
-    if (pm10 >= 0) {
+    if (utils::isValidPMS(pm10)) {
       add_metric("pm10",
                  "PM10 concentration as measured by the AirGradient PMS "
                  "sensor, in micrograms per cubic meter",
                  "gauge", "ugm3");
       add_metric_point("", String(pm10));
     }
-    if (pm03PCount >= 0) {
+    if (utils::isValidPMS03Count(pm03PCount)) {
       add_metric("pm0d3",
                  "PM0.3 concentration as measured by the AirGradient PMS "
                  "sensor, in number of particules per 100 milliliters",
@@ -154,28 +154,28 @@ String OpenMetrics::getPayload(void) {
   }
 
   if (config.hasSensorSGP) {
-    if (measure.TVOC >= 0) {
+    if (utils::isValidVOC(measure.TVOC)) {
       add_metric("tvoc_index",
                  "The processed Total Volatile Organic Compounds (TVOC) index "
                  "as measured by the AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.TVOC));
     }
-    if (measure.TVOCRaw >= 0) {
+    if (utils::isValidVOC(measure.TVOCRaw)) {
       add_metric("tvoc_raw",
                  "The raw input value to the Total Volatile Organic Compounds "
                  "(TVOC) index as measured by the AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.TVOCRaw));
     }
-    if (measure.NOx >= 0) {
+    if (utils::isValidNOx(measure.NOx)) {
       add_metric("nox_index",
                  "The processed Nitrous Oxide (NOx) index as measured by the "
                  "AirGradient SGP sensor",
                  "gauge");
       add_metric_point("", String(measure.NOx));
     }
-    if (measure.NOxRaw >= 0) {
+    if (utils::isValidNOx(measure.NOxRaw)) {
       add_metric("nox_raw",
                  "The raw input value to the Nitrous Oxide (NOx) index as "
                  "measured by the AirGradient SGP sensor",
@@ -184,14 +184,14 @@ String OpenMetrics::getPayload(void) {
     }
   }
 
-  if (_temp > -1001) {
+  if (utils::isValidTemperature(_temp)) {
     add_metric("temperature",
                "The ambient temperature as measured by the AirGradient SHT / PMS "
                "sensor, in degrees Celsius",
                "gauge", "celsius");
     add_metric_point("", String(_temp));
   }
-  if (atmpCompensated > -1001) {
+  if (utils::isValidTemperature(atmpCompensated)) {
     add_metric(
         "temperature_compensated",
         "The compensated ambient temperature as measured by the AirGradient SHT / PMS "
@@ -199,14 +199,14 @@ String OpenMetrics::getPayload(void) {
         "gauge", "celsius");
     add_metric_point("", String(atmpCompensated));
   }
-  if (_hum >= 0) {
+  if (utils::isValidHumidity(_hum)) {
     add_metric(
         "humidity",
         "The relative humidity as measured by the AirGradient SHT sensor",
         "gauge", "percent");
     add_metric_point("", String(_hum));
   }
-  if (ahumCompensated >= 0) {
+  if (utils::isValidHumidity(ahumCompensated)) {
     add_metric(
         "humidity_compensated",
         "The compensated relative humidity as measured by the AirGradient SHT / PMS sensor",
diff --git a/src/AgApiClient.cpp b/src/AgApiClient.cpp
index bff6789..d64c8e3 100644
--- a/src/AgApiClient.cpp
+++ b/src/AgApiClient.cpp
@@ -66,6 +66,10 @@ bool AgApiClient::fetchServerConfiguration(void) {
 
   /** Get data */
   int retCode = client.GET();
+
+  logInfo(String("GET: ") + uri);
+  logInfo(String("Return code: ") + String(retCode));
+
   if (retCode != 200) {
     client.end();
     getConfigFailed = true;
@@ -109,20 +113,25 @@ bool AgApiClient::postToServer(String data) {
     return false;
   }
 
-  String uri = apiRoot + "/sensors/airgradient:" +
-               ag->deviceId() + "/measures";
-  logInfo("Post uri: " + uri);
-  logInfo("Post data: " + data);
+  String uri =
+      "http://hw.airgradient.com/sensors/airgradient:" + ag->deviceId() +
+      "/measures";
+  // logInfo("Post uri: " + uri);
+  // logInfo("Post data: " + data);
 
   WiFiClient wifiClient;
   HTTPClient client;
   if (client.begin(wifiClient, uri.c_str()) == false) {
+    logError("Init client failed");
     return false;
   }
   client.addHeader("content-type", "application/json");
   int retCode = client.POST(data);
   client.end();
 
+  logInfo(String("POST: ") + uri);
+  logInfo(String("Return code: ") + String(retCode));
+
   if ((retCode == 200) || (retCode == 429)) {
     postToServerFailed = false;
     return true;
diff --git a/src/AgOledDisplay.cpp b/src/AgOledDisplay.cpp
index 22d25b2..8b07ada 100644
--- a/src/AgOledDisplay.cpp
+++ b/src/AgOledDisplay.cpp
@@ -1,5 +1,6 @@
 #include "AgOledDisplay.h"
 #include "Libraries/U8g2/src/U8g2lib.h"
+#include "Main/utils.h"
 
 /** Cast U8G2 */
 #define DISP() ((U8G2_SH1106_128X64_NONAME_F_HW_I2C *)(this->u8g2))
@@ -10,8 +11,8 @@
  * @param hasStatus
  */
 void OledDisplay::showTempHum(bool hasStatus) {
-  char buf[10];
-  if (value.Temperature > -1001) {
+  char buf[16];
+  if (utils::isValidTemperature(value.Temperature)) {
     if (config.isTemperatureUnitInF()) {
       float tempF = (value.Temperature * 9) / 5 + 32;
       if (hasStatus) {
@@ -36,10 +37,10 @@ void OledDisplay::showTempHum(bool hasStatus) {
   DISP()->drawUTF8(1, 10, buf);
 
   /** Show humidty */
-  if (value.Humidity >= 0) {
+  if (utils::isValidHumidity(value.Humidity)) {
     snprintf(buf, sizeof(buf), "%d%%", value.Humidity);
   } else {
-    snprintf(buf, sizeof(buf), "%-%%");
+    snprintf(buf, sizeof(buf), "-%%");
   }
 
   if (value.Humidity > 99) {
@@ -283,12 +284,8 @@ void OledDisplay::showDashboard(const char *status) {
       DISP()->drawUTF8(1, 27, "CO2");
 
       DISP()->setFont(u8g2_font_t0_22b_tf);
-      if (value.CO2 > 0) {
-        int val = 9999;
-        if (value.CO2 < 10000) {
-          val = value.CO2;
-        }
-        sprintf(strBuf, "%d", val);
+      if (utils::isValidCO2(value.CO2)) {
+        sprintf(strBuf, "%d", value.CO2);
       } else {
         sprintf(strBuf, "%s", "-");
       }
@@ -299,88 +296,111 @@ void OledDisplay::showDashboard(const char *status) {
       DISP()->drawStr(1, 61, "ppm");
 
       /** Draw vertical line */
-      DISP()->drawLine(45, 14, 45, 64);
-      DISP()->drawLine(82, 14, 82, 64);
+      DISP()->drawLine(52, 14, 52, 64);
+      DISP()->drawLine(97, 14, 97, 64);
 
       /** Draw PM2.5 label */
       DISP()->setFont(u8g2_font_t0_12_tf);
-      DISP()->drawStr(48, 27, "PM2.5");
+      DISP()->drawStr(55, 27, "PM2.5");
 
       /** Draw PM2.5 value */
+      int pm25 = value.pm25_1;
+      if (config.hasSensorSHT) {
+        pm25 = ag->pms5003.compensated(pm25, value.Humidity);
+      }
       DISP()->setFont(u8g2_font_t0_22b_tf);
       if (config.isPmStandardInUSAQI()) {
-        if (value.pm25_1 >= 0) {
+        if (utils::isValidPMS(value.pm25_1)) {
           sprintf(strBuf, "%d", ag->pms5003.convertPm25ToUsAqi(value.pm25_1));
         } else {
           sprintf(strBuf, "%s", "-");
         }
-        DISP()->drawStr(48, 48, strBuf);
+        DISP()->drawStr(55, 48, strBuf);
         DISP()->setFont(u8g2_font_t0_12_tf);
-        DISP()->drawUTF8(48, 61, "AQI");
+        DISP()->drawUTF8(55, 61, "AQI");
       } else {
-        if (value.pm25_1 >= 0) {
+        if (utils::isValidPMS(value.pm25_1)) {
           sprintf(strBuf, "%d", value.pm25_1);
         } else {
           sprintf(strBuf, "%s", "-");
         }
-        DISP()->drawStr(48, 48, strBuf);
+        DISP()->drawStr(55, 48, strBuf);
         DISP()->setFont(u8g2_font_t0_12_tf);
-        DISP()->drawUTF8(48, 61, "ug/m³");
+        DISP()->drawUTF8(55, 61, "ug/m³");
       }
 
       /** Draw tvocIndexlabel */
       DISP()->setFont(u8g2_font_t0_12_tf);
-      DISP()->drawStr(85, 27, "tvoc:");
+      DISP()->drawStr(100, 27, "VOC:");
 
       /** Draw tvocIndexvalue */
-      if (value.TVOC >= 0) {
+      if (utils::isValidVOC(value.TVOC)) {
         sprintf(strBuf, "%d", value.TVOC);
       } else {
         sprintf(strBuf, "%s", "-");
       }
-      DISP()->drawStr(85, 39, strBuf);
+      DISP()->drawStr(100, 39, strBuf);
 
       /** Draw NOx label */
-      DISP()->drawStr(85, 53, "NOx:");
-      if (value.NOx >= 0) {
+      DISP()->drawStr(100, 53, "NOx:");
+      if (utils::isValidNOx(value.NOx)) {
         sprintf(strBuf, "%d", value.NOx);
       } else {
         sprintf(strBuf, "%s", "-");
       }
-      DISP()->drawStr(85, 63, strBuf);
+      DISP()->drawStr(100, 63, strBuf);
     } while (DISP()->nextPage());
   } else if (ag->isBasic()) {
     ag->display.clear();
 
     /** Set CO2 */
-    snprintf(strBuf, sizeof(strBuf), "CO2:%d", value.CO2);
+    if(utils::isValidCO2(value.CO2)) {
+      snprintf(strBuf, sizeof(strBuf), "CO2:%d", value.CO2);
+    } else {
+      snprintf(strBuf, sizeof(strBuf), "CO2:-");
+    }
+    
     ag->display.setCursor(0, 0);
     ag->display.setText(strBuf);
 
     /** Set PM */
+    int pm25 = value.pm25_1;
+    if(config.hasSensorSHT) {
+      pm25 = (int)ag->pms5003.compensated(pm25, value.Humidity);
+    }
     ag->display.setCursor(0, 12);
-    snprintf(strBuf, sizeof(strBuf), "PM2.5:%d", value.pm25_1);
+    if (utils::isValidPMS(value.pm25_1)) {
+      snprintf(strBuf, sizeof(strBuf), "PM2.5:%d", value.pm25_1);
+    } else {
+      snprintf(strBuf, sizeof(strBuf), "PM2.5:-");
+    }
     ag->display.setText(strBuf);
 
     /** Set temperature and humidity */
-    if (value.Temperature <= -1001.0f) {
+    if (utils::isValidTemperature(value.Temperature)) {
+      if (config.isTemperatureUnitInF()) {
+        float tempF = (value.Temperature * 9) / 5 + 32;
+        snprintf(strBuf, sizeof(strBuf), "T:%0.1f F", tempF);
+      } else {
+        snprintf(strBuf, sizeof(strBuf), "T:%0.f1 C", value.Temperature);
+      }
+    } else {
       if (config.isTemperatureUnitInF()) {
         snprintf(strBuf, sizeof(strBuf), "T:-F");
       } else {
         snprintf(strBuf, sizeof(strBuf), "T:-C");
       }
-    } else {
-      if (config.isTemperatureUnitInF()) {
-        float tempF = (value.Temperature * 9) / 5 + 32;
-        snprintf(strBuf, sizeof(strBuf), "T:%d F", (int)tempF);
-      } else {
-        snprintf(strBuf, sizeof(strBuf), "T:%d C", (int)value.Temperature);
-      }
     }
+
     ag->display.setCursor(0, 24);
     ag->display.setText(strBuf);
 
-    snprintf(strBuf, sizeof(strBuf), "H:%d %%", (int)value.Humidity);
+    if (utils::isValidHumidity(value.Humidity)) {
+      snprintf(strBuf, sizeof(strBuf), "H:%d %%", (int)value.Humidity);
+    } else {
+      snprintf(strBuf, sizeof(strBuf), "H:- %%");
+    }
+
     ag->display.setCursor(0, 36);
     ag->display.setText(strBuf);
 
diff --git a/src/AgStateMachine.cpp b/src/AgStateMachine.cpp
index 58d777c..b6e9610 100644
--- a/src/AgStateMachine.cpp
+++ b/src/AgStateMachine.cpp
@@ -9,9 +9,9 @@
 
 #define RGB_COLOR_R 255, 0, 0    /** Red */
 #define RGB_COLOR_G 0, 255, 0    /** Green */
-#define RGB_COLOR_Y 255, 255, 0  /** Yellow */
-#define RGB_COLOR_O 255, 165, 0  /** Organge */
-#define RGB_COLOR_P 160, 32, 240 /** Purple */
+#define RGB_COLOR_Y 255, 150, 0  /** Yellow */
+#define RGB_COLOR_O 255, 40, 0  /** Orange */
+#define RGB_COLOR_P 180, 0, 255 /** Purple */
 
 /**
  * @brief Animation LED bar with color
@@ -573,7 +573,7 @@ void StateMachine::handleLeds(AgStateMachineState state) {
   case AgStateMachineWiFiManagerMode: {
     /** In WiFi Manager Mode */
     /** Turn LED OFF */
-    /** Turn midle LED Color */
+    /** Turn middle LED Color */
     if (ag->isOne()) {
       ag->ledBar.setColor(0, 0, 255, ag->ledBar.getNumberOfLeds() / 2);
     } else {
@@ -713,7 +713,7 @@ void StateMachine::handleLeds(AgStateMachineState state) {
     break;
   }
   case AgStateMachineSensorConfigFailed: {
-    /** Server is reachable but there is some configuration issue to be fixed on
+    /** Server is reachable but there is some configuration issue to be fixed on
      * the server side */
     if (ag->isOne()) {
       ag->ledBar.setColor(139, 24, 248, 0);
diff --git a/src/AgValue.cpp b/src/AgValue.cpp
index bd729ea..015a788 100644
--- a/src/AgValue.cpp
+++ b/src/AgValue.cpp
@@ -1,6 +1,7 @@
 #include "AgValue.h"
 #include "AgConfigure.h"
 #include "AirGradient.h"
+#include "Main/utils.h"
 #include "Libraries/Arduino_JSON/src/Arduino_JSON.h"
 
 String Measurements::toString(bool localServer, AgFirmwareMode fwMode, int rssi,
@@ -13,36 +14,35 @@ String Measurements::toString(bool localServer, AgFirmwareMode fwMode, int rssi,
   if (localServer) {
     root["serialno"] = ag->deviceId();
   }
-  if (config->hasSensorS8) {
-    if (this->CO2 >= 0) {
-      root["rco2"] = this->CO2;
-    }
+
+  if (config->hasSensorS8 && utils::isValidCO2(this->CO2)) {
+    root["rco2"] = this->CO2;
   }
 
   if (ag->isOne() || (ag->isPro4_2()) || ag->isPro3_3() || ag->isBasic()) {
     if (config->hasSensorPMS1) {
-      if (this->pm01_1 >= 0) {
+      if (utils::isValidPMS(this->pm01_1)) {
         root["pm01"] = this->pm01_1;
       }
-      if (this->pm25_1 >= 0) {
+      if (utils::isValidPMS(this->pm25_1)) {
         root["pm02"] = this->pm25_1;
       }
-      if (this->pm10_1 >= 0) {
+      if (utils::isValidPMS(this->pm10_1)) {
         root["pm10"] = this->pm10_1;
       }
-      if (this->pm03PCount_1 >= 0) {
+      if (utils::isValidPMS03Count(this->pm03PCount_1)) {
         root["pm003Count"] = this->pm03PCount_1;
       }
     }
 
     if (config->hasSensorSHT) {
-      if (this->Temperature > -1001) {
+      if (utils::isValidTemperature(this->Temperature)) {
         root["atmp"] = ag->round2(this->Temperature);
         if (localServer) {
           root["atmpCompensated"] = ag->round2(this->Temperature);
         }
       }
-      if (this->Humidity >= 0) {
+      if (utils::isValidHumidity(this->Humidity)) {
         root["rhum"] = this->Humidity;
         if (localServer) {
           root["rhumCompensated"] = this->Humidity;
@@ -50,126 +50,287 @@ String Measurements::toString(bool localServer, AgFirmwareMode fwMode, int rssi,
       }
     }
 
-  } else {
-    if (config->hasSensorPMS1 && config->hasSensorPMS2) {
-      root["pm01"] = ag->round2((this->pm01_1 + this->pm01_2) / 2.0);
-      root["pm02"] = ag->round2((this->pm25_1 + this->pm25_2) / 2.0);
-      root["pm10"] = ag->round2((this->pm10_1 + this->pm10_2) / 2.0);
-      root["pm003Count"] =
-          ag->round2((this->pm03PCount_1 + this->pm03PCount_2) / 2.0);
-      root["atmp"] = ag->round2((this->temp_1 + this->temp_2) / 2.0f);
-      root["rhum"] = ag->round2((this->hum_1 + this->hum_2) / 2.0f);
-      if (localServer) {
-        root["atmpCompensated"] =
-            ag->round2(ag->pms5003t_2.temperatureCompensated(
-                (this->temp_1 + this->temp_2) / 2.0f));
-        root["rhumCompensated"] = (int)ag->pms5003t_2.humidityCompensated(
-            (this->hum_1 + this->hum_2) / 2.0f);
+    if (config->hasSensorSHT && config->hasSensorPMS1) {
+      int pm25 = ag->pms5003.compensated(this->pm25_1, this->Humidity);
+      if (pm25 >= 0) {
+        root["pm02Compensated"] = pm25;
       }
     }
 
-    if (fwMode == FW_MODE_O_1PS || fwMode == FW_MODE_O_1PST) {
-      if (config->hasSensorPMS1) {
-        root["pm01"] = this->pm01_1;
-        root["pm02"] = this->pm25_1;
-        root["pm10"] = this->pm10_1;
-        root["pm003Count"] = this->pm03PCount_1;
-        root["atmp"] = ag->round2(this->temp_1);
-        root["rhum"] = this->hum_1;
+  } else {
+    if (config->hasSensorPMS1 && config->hasSensorPMS2) {
+      if (utils::isValidPMS(this->pm01_1) && utils::isValidPMS(this->pm01_2)) {
+        root["pm01"] = ag->round2((this->pm01_1 + this->pm01_2) / 2.0f);
+      }
+      if (utils::isValidPMS(this->pm25_1) && utils::isValidPMS(this->pm25_2)) {
+        root["pm02"] = ag->round2((this->pm25_1 + this->pm25_2) / 2.0f);
+      }
+      if (utils::isValidPMS(this->pm10_1) && utils::isValidPMS(this->pm10_2)) {
+        root["pm10"] = ag->round2((this->pm10_1 + this->pm10_2) / 2.0f);
+      }
+      if (utils::isValidPMS(this->pm03PCount_1) && utils::isValidPMS(this->pm03PCount_2)) {
+        root["pm003Count"] = ag->round2((this->pm03PCount_1 + this->pm03PCount_2) / 2.0f);
+      }
+
+      float val;
+      if (utils::isValidTemperature(this->temp_1) && utils::isValidTemperature(this->temp_1)) {
+        root["atmp"] = ag->round2((this->temp_1 + this->temp_2) / 2.0f);
         if (localServer) {
-          root["atmpCompensated"] =
-              ag->round2(ag->pms5003t_1.temperatureCompensated(this->temp_1));
-          root["rhumCompensated"] =
-              (int)ag->pms5003t_1.humidityCompensated(this->hum_1);
+          val = ag->pms5003t_2.temperatureCompensated((this->temp_1 + this->temp_2) / 2.0f);
+          if (utils::isValidTemperature(val)) {
+            root["atmpCompensated"] = ag->round2(val);
+          }
         }
       }
-      if (config->hasSensorPMS2) {
-        root["pm01"] = this->pm01_2;
-        root["pm02"] = this->pm25_2;
-        root["pm10"] = this->pm10_2;
-        root["pm003Count"] = this->pm03PCount_2;
-        root["atmp"] = ag->round2(this->temp_2);
-        root["rhum"] = this->hum_2;
+      if (utils::isValidHumidity(this->hum_1) && utils::isValidHumidity(this->hum_1)) {
+        root["rhum"] = ag->round2((this->hum_1 + this->hum_2) / 2.0f);
         if (localServer) {
-          root["atmpCompensated"] =
-              ag->round2(ag->pms5003t_2.temperatureCompensated(this->temp_2));
-          root["rhumCompensated"] =
-              (int)ag->pms5003t_2.humidityCompensated(this->hum_2);
+          val = ag->pms5003t_2.humidityCompensated((this->hum_1 + this->hum_2) / 2.0f);
+          if (utils::isValidHumidity(val)) {
+            root["rhumCompensated"] = (int)val;
+          }
         }
       }
+
+      int pm25 = (ag->pms5003t_1.compensated(this->pm25_1, this->temp_1) +
+                  ag->pms5003t_2.compensated(this->pm25_2, this->temp_2)) /
+                 2;
+      root["pm02Compensated"] = pm25;
+    }
+
+    if (fwMode == FW_MODE_O_1PS || fwMode == FW_MODE_O_1PST) {
+      float val;
+      if (config->hasSensorPMS1) {
+        if (utils::isValidPMS(this->pm01_1)) {
+          root["pm01"] = this->pm01_1;
+        }
+        if (utils::isValidPMS(this->pm25_1)) {
+          root["pm02"] = this->pm25_1;
+        }
+        if (utils::isValidPMS(this->pm10_1)) {
+          root["pm10"] = this->pm10_1;
+        }
+        if (utils::isValidPMS03Count(this->pm03PCount_1)) {
+          root["pm003Count"] = this->pm03PCount_1;
+        }
+        if (utils::isValidTemperature(this->temp_1)) {
+          root["atmp"] = ag->round2(this->temp_1);
+
+          if (localServer) {
+            val = ag->pms5003t_1.temperatureCompensated(this->temp_1);
+            if (utils::isValidTemperature(val)) {
+              root["atmpCompensated"] = ag->round2(val);
+            }
+          }
+        }
+        if (utils::isValidHumidity(this->hum_1)) {
+          root["rhum"] = this->hum_1;
+
+          if (localServer) {
+            val = ag->pms5003t_1.humidityCompensated(this->hum_1);
+            if (utils::isValidHumidity(val)) {
+              root["rhumCompensated"] = (int)val;
+            }
+          }
+        }
+        root["pm02Compensated"] = ag->pms5003t_1.compensated(this->pm25_1, this->temp_1);
+      }
+      if (config->hasSensorPMS2) {
+        if(utils::isValidPMS(this->pm01_2)) {
+          root["pm01"] = this->pm01_2;
+        }
+        if(utils::isValidPMS(this->pm25_2)) {
+          root["pm02"] = this->pm25_2;
+        }
+        if(utils::isValidPMS(this->pm10_2)) {
+          root["pm10"] = this->pm10_2;
+        }
+        if(utils::isValidPMS03Count(this->pm03PCount_2)) {
+          root["pm003Count"] = this->pm03PCount_2;
+        }
+
+        float val;
+        if (utils::isValidTemperature(this->temp_2)) {
+          root["atmp"] = ag->round2(this->temp_2);
+
+          if (localServer) {
+            val = ag->pms5003t_2.temperatureCompensated(this->temp_2);
+            if (utils::isValidTemperature(val)) {
+              root["atmpCompensated"] = ag->round2(val);
+            }
+          }
+        }
+        if(utils::isValidHumidity(this->hum_2)) {
+          root["rhum"] = this->hum_2;
+
+          if (localServer) {
+            val = ag->pms5003t_2.humidityCompensated(this->hum_2);
+            if (utils::isValidHumidity(val)) {
+              root["rhumCompensated"] = (int)val;
+            }
+          }
+        }
+        root["pm02Compensated"] = ag->pms5003t_2.compensated(this->pm25_2, this->temp_2);
+      }
     } else {
       if (fwMode == FW_MODE_O_1P) {
+        float val;
         if (config->hasSensorPMS1) {
-          root["pm01"] = this->pm01_1;
-          root["pm02"] = this->pm25_1;
-          root["pm10"] = this->pm10_1;
-          root["pm003Count"] = this->pm03PCount_1;
-          root["atmp"] = ag->round2(this->temp_1);
-          root["rhum"] = this->hum_1;
-          if (localServer) {
-            root["atmpCompensated"] =
-                ag->round2(ag->pms5003t_1.temperatureCompensated(this->temp_1));
-            root["rhumCompensated"] =
-                (int)ag->pms5003t_1.humidityCompensated(this->hum_1);
+          if (utils::isValidPMS(this->pm01_1)) {
+            root["pm01"] = this->pm01_1;
           }
+          if (utils::isValidPMS(this->pm25_1)) {
+            root["pm02"] = this->pm25_1;
+          }
+          if (utils::isValidPMS(this->pm10_1)) {
+            root["pm10"] = this->pm10_1;
+          }
+          if (utils::isValidPMS03Count(this->pm03PCount_1)) {
+            root["pm003Count"] = this->pm03PCount_1;
+          }
+          if (utils::isValidTemperature(this->temp_1)) {
+            root["atmp"] = ag->round2(this->temp_1);
+
+            if (localServer) {
+              val = ag->pms5003t_1.temperatureCompensated(this->temp_1);
+              if (utils::isValidTemperature(val)) {
+                root["atmpCompensated"] = ag->round2(val);
+              }
+            }
+          }
+          if (utils::isValidHumidity(this->hum_1)) {
+            root["rhum"] = this->hum_1;
+            if(localServer) {
+              val = ag->pms5003t_1.humidityCompensated(this->hum_1);
+              if(utils::isValidHumidity(val)) {
+                root["rhumCompensated"] = (int)val;
+              }
+            }
+          }
+          root["pm02Compensated"] = ag->pms5003t_1.compensated(this->pm25_1, this->temp_1);
         } else if (config->hasSensorPMS2) {
-          root["pm01"] = this->pm01_2;
-          root["pm02"] = this->pm25_2;
-          root["pm10"] = this->pm10_2;
-          root["pm003Count"] = this->pm03PCount_2;
-          root["atmp"] = ag->round2(this->temp_2);
-          root["rhum"] = this->hum_2;
-          if (localServer) {
-            root["atmpCompensated"] =
-                ag->round2(ag->pms5003t_1.temperatureCompensated(this->temp_2));
-            root["rhumCompensated"] =
-                (int)ag->pms5003t_1.humidityCompensated(this->hum_2);
+          if(utils::isValidPMS(this->pm01_2)) {
+            root["pm01"] = this->pm01_2;
           }
+          if(utils::isValidPMS(this->pm25_2)) {
+            root["pm02"] = this->pm25_2;
+          }
+          if(utils::isValidPMS(this->pm10_2)) {
+            root["pm10"] = this->pm10_2;
+          }
+          if(utils::isValidPMS03Count(this->pm03PCount_2)) {
+            root["pm003Count"] = this->pm03PCount_2;
+          }
+          if (utils::isValidTemperature(this->temp_2)) {
+            root["atmp"] = ag->round2(this->temp_2);
+            if (localServer) {
+
+              val = ag->pms5003t_1.temperatureCompensated(this->temp_2);
+              if (utils::isValidTemperature(val)) {
+                root["atmpCompensated"] = ag->round2(val);
+              }
+            }
+          }
+          if (utils::isValidHumidity(this->hum_2)) {
+            root["rhum"] = this->hum_2;
+
+            if(localServer) {
+              val = ag->pms5003t_1.humidityCompensated(this->hum_2);
+              if(utils::isValidHumidity(val)) {
+                root["rhumCompensated"] = (int)val;
+              }
+            }
+          }
+          root["pm02Compensated"] = ag->pms5003t_1.compensated(this->pm25_1, this->temp_1);
         }
       } else {
+        float val;
         if (config->hasSensorPMS1) {
-          root["channels"]["1"]["pm01"] = this->pm01_1;
-          root["channels"]["1"]["pm02"] = this->pm25_1;
-          root["channels"]["1"]["pm10"] = this->pm10_1;
-          root["channels"]["1"]["pm003Count"] = this->pm03PCount_1;
-          root["channels"]["1"]["atmp"] = ag->round2(this->temp_1);
-          root["channels"]["1"]["rhum"] = this->hum_1;
-          if (localServer) {
-            root["channels"]["1"]["atmpCompensated"] =
-                ag->round2(ag->pms5003t_1.temperatureCompensated(this->temp_1));
-            root["channels"]["1"]["rhumCompensated"] =
-                (int)ag->pms5003t_1.humidityCompensated(this->hum_1);
+          if(utils::isValidPMS(this->pm01_1)) {
+            root["channels"]["1"]["pm01"] = this->pm01_1;
           }
+          if(utils::isValidPMS(this->pm25_1)) {
+            root["channels"]["1"]["pm02"] = this->pm25_1;
+          }
+          if(utils::isValidPMS(this->pm10_1)) {
+            root["channels"]["1"]["pm10"] = this->pm10_1;
+          }
+          if (utils::isValidPMS03Count(this->pm03PCount_1)) {
+            root["channels"]["1"]["pm003Count"] = this->pm03PCount_1;
+          }
+          if(utils::isValidTemperature(this->temp_1)) {
+            root["channels"]["1"]["atmp"] = ag->round2(this->temp_1);
+
+            if (localServer) {
+              val = ag->pms5003t_1.temperatureCompensated(this->temp_1);
+              if (utils::isValidTemperature(val)) {
+                root["channels"]["1"]["atmpCompensated"] = ag->round2(val);
+              }
+            }
+          }
+          if (utils::isValidHumidity(this->hum_1)) {
+            root["channels"]["1"]["rhum"] = this->hum_1;
+
+            if (localServer) {
+              val = ag->pms5003t_1.humidityCompensated(this->hum_1);
+              if (utils::isValidHumidity(val)) {
+                root["channels"]["1"]["rhumCompensated"] = (int)val;
+              }
+            }
+          }
+          root["channels"]["1"]["pm02Compensated"] = ag->pms5003t_1.compensated(this->pm25_1, this->temp_1);
         }
         if (config->hasSensorPMS2) {
-          root["channels"]["2"]["pm01"] = this->pm01_2;
-          root["channels"]["2"]["pm02"] = this->pm25_2;
-          root["channels"]["2"]["pm10"] = this->pm10_2;
-          root["channels"]["2"]["pm003Count"] = this->pm03PCount_2;
-          root["channels"]["2"]["atmp"] = ag->round2(this->temp_2);
-          root["channels"]["2"]["rhum"] = this->hum_2;
-          if (localServer) {
-            root["channels"]["2"]["atmpCompensated"] =
-                ag->round2(ag->pms5003t_1.temperatureCompensated(this->temp_2));
-            root["channels"]["2"]["rhumCompensated"] =
-                (int)ag->pms5003t_1.humidityCompensated(this->hum_2);
+          float val;
+          if (utils::isValidPMS(this->pm01_2)) {
+            root["channels"]["2"]["pm01"] = this->pm01_2;
           }
+          if (utils::isValidPMS(this->pm25_2)) {
+            root["channels"]["2"]["pm02"] = this->pm25_2;
+          }
+          if (utils::isValidPMS(this->pm10_2)) {
+            root["channels"]["2"]["pm10"] = this->pm10_2;
+          }
+          if (utils::isValidPMS03Count(this->pm03PCount_2)) {
+            root["channels"]["2"]["pm003Count"] = this->pm03PCount_2;
+          }
+          if (utils::isValidTemperature(this->temp_2)) {
+            root["channels"]["2"]["atmp"] = ag->round2(this->temp_2);
+
+            if (localServer) {
+              val = ag->pms5003t_1.temperatureCompensated(this->temp_2);
+              if (utils::isValidTemperature(val)) {
+                root["channels"]["2"]["atmpCompensated"] = ag->round2(val);
+              }
+            }
+          }
+          if (utils::isValidHumidity(this->hum_2)) {
+            root["channels"]["2"]["rhum"] = this->hum_2;
+
+            if (localServer) {
+              val = ag->pms5003t_1.humidityCompensated(this->hum_2);
+              if (utils::isValidHumidity(val)) {
+                root["channels"]["2"]["rhumCompensated"] = (int)val;
+              }
+            }
+          }
+          root["channels"]["2"]["pm02Compensated"] = ag->pms5003t_2.compensated(this->pm25_2, this->temp_2);
         }
       }
     }
   }
 
   if (config->hasSensorSGP) {
-    if (this->TVOC >= 0) {
+    if (utils::isValidVOC(this->TVOC)) {
       root["tvocIndex"] = this->TVOC;
     }
-    if (this->TVOCRaw >= 0) {
+    if (utils::isValidVOC(this->TVOCRaw)) {
       root["tvocRaw"] = this->TVOCRaw;
     }
-    if (this->NOx >= 0) {
+    if (utils::isValidNOx(this->NOx)) {
       root["noxIndex"] = this->NOx;
     }
-    if (this->NOxRaw >= 0) {
+    if (utils::isValidNOx(this->NOxRaw)) {
       root["noxRaw"] = this->NOxRaw;
     }
   }
diff --git a/src/AirGradient.cpp b/src/AirGradient.cpp
index e036982..46ed874 100644
--- a/src/AirGradient.cpp
+++ b/src/AirGradient.cpp
@@ -41,7 +41,14 @@ String AirGradient::getVersion(void) { return GIT_VERSION; }
 BoardType AirGradient::getBoardType(void) { return boardType; }
 
 double AirGradient::round2(double value) {
-  return (int)(value * 100 + 0.5) / 100.0;
+  double ret;
+  if (value >= 0) {
+    ret = (int)(value * 100 + 0.5f);
+  } else {
+    ret = (int)(value * 100 - 0.5f);
+  }
+
+  return ret / 100;
 }
 
 String AirGradient::getBoardName(void) {
diff --git a/src/AirGradient.h b/src/AirGradient.h
index 5c47e1b..54abd91 100644
--- a/src/AirGradient.h
+++ b/src/AirGradient.h
@@ -12,6 +12,7 @@
 #include "S8/S8.h"
 #include "Sgp41/Sgp41.h"
 #include "Sht/Sht.h"
+#include "Main/utils.h"
 
 #ifndef GIT_VERSION
 #define GIT_VERSION "snapshot"
diff --git a/src/Main/utils.cpp b/src/Main/utils.cpp
new file mode 100644
index 0000000..1c8175d
--- /dev/null
+++ b/src/Main/utils.cpp
@@ -0,0 +1,89 @@
+#include "utils.h"
+
+#define VALID_TEMPERATURE_MAX (125)
+#define VALID_TEMPERATURE_MIN (-40)
+#define INVALID_TEMPERATURE   (-1000)
+
+#define VALID_HUMIDITY_MAX    (100)
+#define VALID_HUMIDITY_MIN    (0)
+#define INVALID_HUMIDITY      (-1)
+
+#define VALID_PMS_MAX         (1000)
+#define VALID_PMS_MIN         (0)
+#define INVALID_PMS           (-1)
+
+#define VALID_PMS03COUNT_MIN  (0)
+
+#define VALID_CO2_MAX         (10000)
+#define VALID_CO2_MIN         (0)
+#define INVALID_CO2           (-1)
+
+#define VALID_NOX_MIN         (0)
+#define VALID_VOC_MIN         (0)
+#define INVALID_NOX           (-1)
+#define INVALID_VOC           (-1)
+
+utils::utils(/* args */) {}
+
+utils::~utils() {}
+
+bool utils::isValidTemperature(float value) {
+  if ((value >= VALID_TEMPERATURE_MIN) && (value <= VALID_TEMPERATURE_MAX)) {
+    return true;
+  }
+  return false;
+}
+
+bool utils::isValidHumidity(float value) {
+  if ((value >= VALID_HUMIDITY_MIN) && (value <= VALID_HUMIDITY_MAX)) {
+    return true;
+  }
+  return false;
+}
+
+bool utils::isValidCO2(int16_t value) {
+  if ((value >= VALID_CO2_MIN) && (value <= VALID_CO2_MAX)) {
+    return true;
+  }
+  return false;
+}
+
+bool utils::isValidPMS(int value) {
+  if ((value >= VALID_PMS_MIN) && (value <= VALID_PMS_MAX)) {
+    return true;
+  }
+  return false;
+}
+
+bool utils::isValidPMS03Count(int value) {
+  if (value >= VALID_PMS03COUNT_MIN) {
+    return true;
+  }
+  return false;
+}
+
+bool utils::isValidNOx(int value) {
+  if (value >= VALID_NOX_MIN) {
+    return true;
+  }
+  return false;
+}
+
+bool utils::isValidVOC(int value) {
+  if (value >= VALID_VOC_MIN) {
+    return true;
+  }
+  return false;
+}
+
+float utils::getInvalidTemperature(void) { return INVALID_TEMPERATURE; }
+
+float utils::getInvalidHumidity(void) { return INVALID_HUMIDITY; }
+
+int utils::getInvalidCO2(void) { return INVALID_CO2; }
+
+int utils::getInvalidPMS(void) { return INVALID_PMS; }
+
+int utils::getInvalidNOx(void) { return INVALID_NOX; }
+
+int utils::getInvalidVOC(void) { return INVALID_VOC; }
diff --git a/src/Main/utils.h b/src/Main/utils.h
new file mode 100644
index 0000000..841d5ec
--- /dev/null
+++ b/src/Main/utils.h
@@ -0,0 +1,30 @@
+#ifndef _UTILS_H_
+#define _UTILS_H_
+
+#include <Arduino.h>
+
+class utils
+{
+private:
+  /* data */
+public:
+  utils(/* args */);
+  ~utils();
+
+  static bool isValidTemperature(float value);
+  static bool isValidHumidity(float value);
+  static bool isValidCO2(int16_t value);
+  static bool isValidPMS(int value);
+  static bool isValidPMS03Count(int value);
+  static bool isValidNOx(int value);
+  static bool isValidVOC(int value);
+  static float getInvalidTemperature(void);
+  static float getInvalidHumidity(void);
+  static int getInvalidCO2(void);
+  static int getInvalidPMS(void);
+  static int getInvalidNOx(void);
+  static int getInvalidVOC(void);
+};
+
+
+#endif /** _UTILS_H_ */
diff --git a/src/PMS/PMS.cpp b/src/PMS/PMS.cpp
index e9a1527..50b3dac 100644
--- a/src/PMS/PMS.cpp
+++ b/src/PMS/PMS.cpp
@@ -3,7 +3,7 @@
 
 /**
  * @brief Init and check that sensor has connected
- * 
+ *
  * @param stream UART stream
  * @return true Sucecss
  * @return false Failure
@@ -86,7 +86,7 @@ void PMSBase::handle() {
     case 2: {
       buf[bufIndex++] = value;
       if (bufIndex >= 4) {
-        len = toValue(&buf[2]);
+        len = toI16(&buf[2]);
         if (len != 28) {
           // Serial.printf("Got good bad len %d\r\n", len);
           len += 4;
@@ -152,98 +152,98 @@ bool PMSBase::isFailed(void) { return failed; }
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getRaw0_1(void) { return toValue(&package[4]); }
+uint16_t PMSBase::getRaw0_1(void) { return toU16(&package[4]); }
 
 /**
  * @brief Read PMS 2.5 ug/m3 with CF = 1 PM estimates
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getRaw2_5(void) { return toValue(&package[6]); }
+uint16_t PMSBase::getRaw2_5(void) { return toU16(&package[6]); }
 
 /**
  * @brief Read PMS 10 ug/m3 with CF = 1 PM estimates
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getRaw10(void) { return toValue(&package[8]); }
+uint16_t PMSBase::getRaw10(void) { return toU16(&package[8]); }
 
 /**
  * @brief Read PMS 0.1 ug/m3
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getPM0_1(void) { return toValue(&package[10]); }
+uint16_t PMSBase::getPM0_1(void) { return toU16(&package[10]); }
 
 /**
  * @brief Read PMS 2.5 ug/m3
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getPM2_5(void) { return toValue(&package[12]); }
+uint16_t PMSBase::getPM2_5(void) { return toU16(&package[12]); }
 
 /**
  * @brief Read PMS 10 ug/m3
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getPM10(void) { return toValue(&package[14]); }
+uint16_t PMSBase::getPM10(void) { return toU16(&package[14]); }
 
 /**
  * @brief Get numnber concentrations over 0.3 um/0.1L
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getCount0_3(void) { return toValue(&package[16]); }
+uint16_t PMSBase::getCount0_3(void) { return toU16(&package[16]); }
 
 /**
  * @brief Get numnber concentrations over 0.5 um/0.1L
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getCount0_5(void) { return toValue(&package[18]); }
+uint16_t PMSBase::getCount0_5(void) { return toU16(&package[18]); }
 
 /**
  * @brief Get numnber concentrations over 1.0 um/0.1L
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getCount1_0(void) { return toValue(&package[20]); }
+uint16_t PMSBase::getCount1_0(void) { return toU16(&package[20]); }
 
 /**
  * @brief Get numnber concentrations over 2.5 um/0.1L
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getCount2_5(void) { return toValue(&package[22]); }
+uint16_t PMSBase::getCount2_5(void) { return toU16(&package[22]); }
 
 /**
  * @brief Get numnber concentrations over 5.0 um/0.1L (only PMS5003)
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getCount5_0(void) { return toValue(&package[24]); }
+uint16_t PMSBase::getCount5_0(void) { return toU16(&package[24]); }
 
 /**
  * @brief Get numnber concentrations over 10.0 um/0.1L (only PMS5003)
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getCount10(void) { return toValue(&package[26]); }
+uint16_t PMSBase::getCount10(void) { return toU16(&package[26]); }
 
 /**
  * @brief Get temperature (only PMS5003T)
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getTemp(void) { return toValue(&package[24]); }
+int16_t PMSBase::getTemp(void) { return toI16(&package[24]); }
 
 /**
  * @brief Get humidity (only PMS5003T)
  *
  * @return uint16_t
  */
-uint16_t PMSBase::getHum(void) { return toValue(&package[26]); }
+uint16_t PMSBase::getHum(void) { return toU16(&package[26]); }
 
 /**
  * @brief Convert PMS2.5 to US AQI unit
@@ -270,13 +270,58 @@ int PMSBase::pm25ToAQI(int pm02) {
     return 500;
 }
 
+/**
+ * @brief Correction PM2.5
+ * 
+ * @param pm25 Raw PM2.5 value
+ * @param humidity Humidity value (%)
+ * @return int 
+ */
+int PMSBase::compensated(int pm25, float humidity) {
+  float value;
+  if (humidity < 0) {
+    humidity = 0;
+  }
+  if (humidity > 100) {
+    humidity = 100;
+  }
+
+  if(pm25 < 30) {
+    value = (pm25 * 0.524f) - (humidity * 0.0862f) + 5.75f;
+  } else if(pm25 < 50) {
+    value = (0.786f * (pm25 / 20 - 3 / 2) + 0.524f * (1 - (pm25 / 20 - 3 / 2))) * pm25 - (0.0862f * humidity) + 5.75f;
+  } else if(pm25 < 210) {
+    value = (0.786f * pm25) - (0.0862f * humidity) + 5.75f;
+  } else if(pm25 < 260) {
+    value = (0.69f * (pm25/50 - 21/5) + 0.786f * (1 - (pm25/50 - 21/5))) * pm25 - (0.0862f * humidity * (1 - (pm25/50 - 21/5))) + (2.966f * (pm25/50 -21/5)) + (5.75f * (1 - (pm25/50 - 21/5))) + (8.84f * (1.e-4) * pm25* (pm25/50 - 21/5));
+  } else {
+    value = 2.966f + (0.69f * pm25) + (8.84f * (1.e-4) * pm25);
+  }
+
+  if(value < 0) {
+    value = 0;
+  }
+
+  return (int)value;
+}
+
 /**
  * @brief   Convert two byte value to uint16_t value
  *
  * @param buf bytes array (must be >= 2)
- * @return uint16_t
+ * @return int16_t
  */
-uint16_t PMSBase::toValue(char *buf) { return (buf[0] << 8) | buf[1]; }
+int16_t PMSBase::toI16(char *buf) {
+  int16_t value = buf[0];
+  value = (value << 8) | buf[1];
+  return value;
+}
+
+uint16_t PMSBase::toU16(char *buf) {
+  uint16_t value = buf[0];
+  value = (value << 8) | buf[1];
+  return value;
+}
 
 /**
  * @brief Validate package data
@@ -290,7 +335,7 @@ bool PMSBase::validate(char *buf) {
   for (int i = 0; i < 30; i++) {
     sum += buf[i];
   }
-  if (sum == toValue(&buf[30])) {
+  if (sum == toU16(&buf[30])) {
     for (int i = 0; i < 32; i++) {
       package[i] = buf[i];
     }
diff --git a/src/PMS/PMS.h b/src/PMS/PMS.h
index 4fa086a..e89693f 100644
--- a/src/PMS/PMS.h
+++ b/src/PMS/PMS.h
@@ -24,10 +24,11 @@ public:
   uint16_t getCount10(void);
 
   /** For PMS5003T*/
-  uint16_t getTemp(void);
+  int16_t getTemp(void);
   uint16_t getHum(void);
 
   int pm25ToAQI(int pm02);
+  int compensated(int pm25, float humidity);
 
 private:
   Stream *stream;
@@ -36,7 +37,8 @@ private:
   bool failed = false;
   uint32_t lastRead;
 
-  uint16_t toValue(char *buf);
+  int16_t toI16(char *buf);
+  uint16_t toU16(char* buf);
   bool validate(char *buf);
 };
 
diff --git a/src/PMS/PMS5003.cpp b/src/PMS/PMS5003.cpp
index 0e7c68b..8a49550 100644
--- a/src/PMS/PMS5003.cpp
+++ b/src/PMS/PMS5003.cpp
@@ -1,5 +1,6 @@
 #include "PMS5003.h"
 #include "Arduino.h"
+#include "../Main/utils.h"
 
 #if defined(ESP8266)
 #include <SoftwareSerial.h>
@@ -108,7 +109,9 @@ int PMS5003::getPm10Ae(void) { return pms.getPM10(); }
  *
  * @return int PM0.3 index
  */
-int PMS5003::getPm03ParticleCount(void) { return pms.getCount0_3(); }
+int PMS5003::getPm03ParticleCount(void) {
+  return pms.getCount0_3();
+}
 
 /**
  * @brief Convert PM2.5 to US AQI
@@ -118,6 +121,17 @@ int PMS5003::getPm03ParticleCount(void) { return pms.getCount0_3(); }
  */
 int PMS5003::convertPm25ToUsAqi(int pm25) { return pms.pm25ToAQI(pm25); }
 
+/**
+ * @brief Correct PM2.5
+ * 
+ * @param pm25 PM2.5 raw value
+ * @param humidity Humidity value
+ * @return float 
+ */
+int PMS5003::compensated(int pm25, float humidity) {
+  return pms.compensated(pm25, humidity);
+}
+
 /**
  * @brief Check device initialized or not
  *
diff --git a/src/PMS/PMS5003.h b/src/PMS/PMS5003.h
index cd66b07..aa6fcd9 100644
--- a/src/PMS/PMS5003.h
+++ b/src/PMS/PMS5003.h
@@ -24,6 +24,7 @@ public:
   int getPm10Ae(void);
   int getPm03ParticleCount(void);
   int convertPm25ToUsAqi(int pm25);
+  int compensated(int pm25, float humidity);
 
 private:
   bool _isBegin = false;
diff --git a/src/PMS/PMS5003T.cpp b/src/PMS/PMS5003T.cpp
index f0f9a1d..97cc9c7 100644
--- a/src/PMS/PMS5003T.cpp
+++ b/src/PMS/PMS5003T.cpp
@@ -1,5 +1,6 @@
 #include "PMS5003T.h"
 #include "Arduino.h"
+#include "../Main/utils.h"
 
 #if defined(ESP8266)
 #include <SoftwareSerial.h>
@@ -133,7 +134,9 @@ int PMS5003T::getPm10Ae(void) { return pms.getPM10(); }
  *
  * @return int PM 0.3 Count index
  */
-int PMS5003T::getPm03ParticleCount(void) { return pms.getCount0_3(); }
+int PMS5003T::getPm03ParticleCount(void) {
+  return pms.getCount0_3();
+}
 
 /**
  * @brief Convert PM2.5 to US AQI
@@ -149,7 +152,7 @@ int PMS5003T::convertPm25ToUsAqi(int pm25) { return pms.pm25ToAQI(pm25); }
  * @return float Degree Celcius
  */
 float PMS5003T::getTemperature(void) {
-  return pms.getTemp()/10.0f;
+  return pms.getTemp() / 10.0f;
 }
 
 /**
@@ -158,7 +161,18 @@ float PMS5003T::getTemperature(void) {
  * @return float Percent (%)
  */
 float PMS5003T::getRelativeHumidity(void) {
-  return pms.getHum()/10.0f;
+  return pms.getHum() / 10.0f;
+}
+
+/**
+ * @brief Correct PM2.5
+ * 
+ * @param pm25 PM2.5 raw value
+ * @param humidity Humidity value
+ * @return float 
+ */
+float PMS5003T::compensated(int pm25, float humidity) {
+  return pms.compensated(pm25, humidity);
 }
 
 /**
diff --git a/src/PMS/PMS5003T.h b/src/PMS/PMS5003T.h
index 2c99b7e..3d2d567 100644
--- a/src/PMS/PMS5003T.h
+++ b/src/PMS/PMS5003T.h
@@ -29,6 +29,7 @@ public:
   int convertPm25ToUsAqi(int pm25);
   float getTemperature(void);
   float getRelativeHumidity(void);
+  float compensated(int pm25, float humidity);
 
 private:
   bool _isBegin = false;
diff --git a/src/S8/S8.cpp b/src/S8/S8.cpp
index c09f0a9..a8f9158 100644
--- a/src/S8/S8.cpp
+++ b/src/S8/S8.cpp
@@ -1,5 +1,6 @@
 #include "S8.h"
 #include "mb_crc.h"
+#include "../Main/utils.h"
 #if defined(ESP8266)
 #include <SoftwareSerial.h>
 #else
@@ -103,7 +104,7 @@ void S8::getFirmwareVersion(char firmver[]) {
  */
 int32_t S8::getSensorTypeId(void) {
   if (this->isBegin() == false) {
-    return -1;
+    return utils::getInvalidCO2();
   }
 
   int32_t sensorType = 0;
diff --git a/src/Sgp41/Sgp41.cpp b/src/Sgp41/Sgp41.cpp
index 502dcb9..3f957a1 100644
--- a/src/Sgp41/Sgp41.cpp
+++ b/src/Sgp41/Sgp41.cpp
@@ -2,6 +2,7 @@
 #include "../Libraries/SensirionSGP41/src/SensirionI2CSgp41.h"
 #include "../Libraries/Sensirion_Gas_Index_Algorithm/src/NOxGasIndexAlgorithm.h"
 #include "../Libraries/Sensirion_Gas_Index_Algorithm/src/VOCGasIndexAlgorithm.h"
+#include "../Main/utils.h"
 
 #define sgpSensor() ((SensirionI2CSgp41 *)(this->_sensor))
 #define vocAlgorithm() ((VOCGasIndexAlgorithm *)(this->_vocAlgorithm))
@@ -66,6 +67,7 @@ bool Sgp41::begin(TwoWire &wire) {
   }
 
   onConditioning = true;
+  _handleFailCount = 0;
 #ifdef ESP32
   /** Create task */
   xTaskCreate(
@@ -108,7 +110,21 @@ void Sgp41::handle(void) {
         noxRaw = srawNox;
         nox = noxAlgorithm()->process(srawNox);
         tvoc = vocAlgorithm()->process(srawVoc);
+
+        _handleFailCount = 0;
         // AgLog("Polling SGP41 success: tvoc: %d, nox: %d", tvoc, nox);
+      } else {
+        if(_handleFailCount < 5) {
+          _handleFailCount++;
+          AgLog("Polling SGP41 failed: %d", _handleFailCount);
+        }
+
+        if (_handleFailCount >= 5) {
+          tvocRaw = utils::getInvalidVOC();
+          tvoc = utils::getInvalidVOC();
+          noxRaw = utils::getInvalidNOx();
+          nox = utils::getInvalidNOx();
+        }
       }
     }
   }
@@ -141,7 +157,21 @@ void Sgp41::_handle(void) {
       noxRaw = srawNox;
       nox = noxAlgorithm()->process(srawNox);
       tvoc = vocAlgorithm()->process(srawVoc);
+
+      _handleFailCount = 0;
       // AgLog("Polling SGP41 success: tvoc: %d, nox: %d", tvoc, nox);
+    } else {
+      if(_handleFailCount < 5) {
+        _handleFailCount++;
+        AgLog("Polling SGP41 failed: %d", _handleFailCount);
+      }
+
+      if (_handleFailCount >= 5) {
+        tvocRaw = utils::getInvalidVOC();
+        tvoc = utils::getInvalidVOC();
+        noxRaw = utils::getInvalidNOx();
+        nox = utils::getInvalidNOx();
+      }
     }
   }
 }
@@ -176,7 +206,7 @@ void Sgp41::end(void) {
  */
 int Sgp41::getTvocIndex(void) {
   if (onConditioning) {
-    return -1;
+    return utils::getInvalidVOC();
   }
   return tvoc;
 }
@@ -188,7 +218,7 @@ int Sgp41::getTvocIndex(void) {
  */
 int Sgp41::getNoxIndex(void) {
   if (onConditioning) {
-    return -1;
+    return utils::getInvalidNOx();
   }
   return nox;
 }
diff --git a/src/Sgp41/Sgp41.h b/src/Sgp41/Sgp41.h
index 9e5674e..381af7f 100644
--- a/src/Sgp41/Sgp41.h
+++ b/src/Sgp41/Sgp41.h
@@ -35,6 +35,7 @@ private:
   bool onConditioning = true;
   bool ready = false;
   bool _isBegin = false;
+  uint8_t _handleFailCount = 0;
   void *_sensor;
   void *_vocAlgorithm;
   void *_noxAlgorithm;
diff --git a/src/Sht/Sht.cpp b/src/Sht/Sht.cpp
index aaba59d..0492ee1 100644
--- a/src/Sht/Sht.cpp
+++ b/src/Sht/Sht.cpp
@@ -1,6 +1,7 @@
 #include "Sht.h"
 
 #include "../Libraries/arduino-sht/SHTSensor.h"
+#include "../Main/utils.h"
 
 /** Cast _sensor to SHTSensor */
 #define shtSensor() ((SHTSensor *)(this->_sensor))
@@ -131,14 +132,18 @@ void Sht::end(void) {
  *
  * @return float
  */
-float Sht::getTemperature(void) { return shtSensor()->getTemperature(); }
+float Sht::getTemperature(void) {
+  return shtSensor()->getTemperature();
+}
 
 /**
  * @brief Get humidity
  *
  * @return float
  */
-float Sht::getRelativeHumidity(void) { return shtSensor()->getHumidity(); }
+float Sht::getRelativeHumidity(void) {
+  return shtSensor()->getHumidity();
+}
 
 /**
  * @brief Measure temperature and humidity