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

INTAKE AIR TEMPERATURE (IAT) SENSOR




The IAT sensor is located in the air induction tubing near the air cleaner element. The IAT sensor is a two wire thermistor type sensor that varies resistance according to changes in air induction temperature. The PCM supplies a five volt reference through a resistor to the sensor, which is connected to ground. When the sensor is cold it has high resistance (high signal voltage at PCM). As the sensor temperature increases, its resistance decreases (lower signal voltage at PCM). The PCM uses the signal voltage to determine intake air temperature.

The PCM uses the IAT sensor for fuel control (calculation of air/fuel mixture temperature at the intake valve in conjunction with the ECT sensor temperature), ignition timing and EVAP purge solenoid control.