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

Intake Air Temperature Sensor:

Intake Air Temperature Sensor Wiring Schematic:

PURPOSE
Air at low temperatures requires a richer air/fuel mixture than air at high temperatures. The Intake Air Temperature (IAT) sensor measures the temperature of the intake air in the air cleaner. The control unit uses this information, compared with information from other sensors, to help determine to the amount of fuel required.

OPERATION
The Intake Air Temperature sensor (IAT) is a thermistor mounted in the air cleaner assembly. Low intake air temperature produces a high resistance, while high intake air temperature produces a low resistance. The ECM supplies a 5.0 volt signal to the sensor through a resistor, and monitors the voltage in the circuit. The measured voltage varies with the temperature of the intake air, due to the changing resistance of the sensor. By measuring the voltage, the ECM can determine the temperature of the incoming air.

A failure in the IAT sensor circuit should set either a DTC 23 or DTC 25. Once a diagnostic trouble code is set, the PCM will use an artificial default value for IAT and some vehicle performance will return.