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

The Intake Air Temperature (IAT) sensor is a thermistor, a resistor which changes value based on the temperature. The IAT sensor measures the temperature of the air entering the engine. Low air temperature produces a high resistance, approximately 100,000 ohms at -40°C (-40°F), while high temperature causes low resistance, approximately 70 ohms at 130°C (266°F). The PCM supplies a 5 volt signal to the IAT sensor through a resistor in the PCM and monitors the terminal voltage. The voltage is high when the intake air is cold, and low when the intake air is hot. By measuring the voltage, the PCM knows the intake air temperature. This air temperature data is used by the PCM in fuel control calculations.

A fault in the EAT sensor circuit should set either a DTC P0112 or DTC P0113.