Air Temperature Sensor ( Ambient / Intake ): Description and Operation

The Intake Air Temperature (IAT) sensor contains a thermistor which changes the resistance based on the temperature. The AT sensor is located in the Mass Air Flow (MAF) sensor. The IAT sensor has a signal circuit and a ground circuit. The Engine Control Module (ECM) applies a voltage, about 5.0 volts, on the signal circuit to the sensor. The ECM monitors any changes in this voltage caused by changes in the resistance of the sensor in order to determine the intake air temperature.

When the intake air is cold, the sensor resistance is high. Therefore, the ECM will sense a high signal voltage or low temperature. When the intake air is warm, the sensor resistance is low. This causes the ECM to sense a low signal voltage or high temperature.

The scan tool displays the temperature of the air entering the engine. This reading should be close to the ambient air temperature when the engine is cold. The temperature reading should rise as the underhood temperature increases. If the engine has not been run for several hours, overnight, the IAT sensor temperature and the engine coolant temperature should be similar.

When the ECM senses a signal voltage outside of the normal operating range of the sensor, DTC P0110 will set.