diff --git a/homeassistant/components/google_assistant/trait.py b/homeassistant/components/google_assistant/trait.py
index 843ebfee87a..c3a7d403a2f 100644
--- a/homeassistant/components/google_assistant/trait.py
+++ b/homeassistant/components/google_assistant/trait.py
@@ -2296,8 +2296,8 @@ class SensorStateTrait(_Trait):
 
     sensor_types = {
         sensor.DEVICE_CLASS_AQI: ("AirQuality", "AQI"),
-        sensor.DEVICE_CLASS_CO: ("CarbonDioxideLevel", "PARTS_PER_MILLION"),
-        sensor.DEVICE_CLASS_CO2: ("CarbonMonoxideLevel", "PARTS_PER_MILLION"),
+        sensor.DEVICE_CLASS_CO: ("CarbonMonoxideLevel", "PARTS_PER_MILLION"),
+        sensor.DEVICE_CLASS_CO2: ("CarbonDioxideLevel", "PARTS_PER_MILLION"),
         sensor.DEVICE_CLASS_PM25: ("PM2.5", "MICROGRAMS_PER_CUBIC_METER"),
         sensor.DEVICE_CLASS_PM10: ("PM10", "MICROGRAMS_PER_CUBIC_METER"),
         sensor.DEVICE_CLASS_VOLATILE_ORGANIC_COMPOUNDS: (
diff --git a/tests/components/google_assistant/test_trait.py b/tests/components/google_assistant/test_trait.py
index a396c1bc91d..278b6dc2ffe 100644
--- a/tests/components/google_assistant/test_trait.py
+++ b/tests/components/google_assistant/test_trait.py
@@ -3030,8 +3030,8 @@ async def test_sensorstate(hass):
     """Test SensorState trait support for sensor domain."""
     sensor_types = {
         sensor.DEVICE_CLASS_AQI: ("AirQuality", "AQI"),
-        sensor.DEVICE_CLASS_CO: ("CarbonDioxideLevel", "PARTS_PER_MILLION"),
-        sensor.DEVICE_CLASS_CO2: ("CarbonMonoxideLevel", "PARTS_PER_MILLION"),
+        sensor.DEVICE_CLASS_CO: ("CarbonMonoxideLevel", "PARTS_PER_MILLION"),
+        sensor.DEVICE_CLASS_CO2: ("CarbonDioxideLevel", "PARTS_PER_MILLION"),
         sensor.DEVICE_CLASS_PM25: ("PM2.5", "MICROGRAMS_PER_CUBIC_METER"),
         sensor.DEVICE_CLASS_PM10: ("PM10", "MICROGRAMS_PER_CUBIC_METER"),
         sensor.DEVICE_CLASS_VOLATILE_ORGANIC_COMPOUNDS: (