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

Temperature Vs. Resistance:

PURPOSE
The Intake Air Temperature (IAT) sensor is a thermistor (a resistor which changes value based on the temperature of air entering the engine) mounted inside the fresh air intake and measures changes in the temperature of the air entering the engine.

OPERATION
Low intake air temperature produces a high IAT sensor resistance, while high intake air temperature produces a low resistance. The Powertrain Control Module (PCM) supplies a 5 volt reference signal and ground to the IAT sensor. The PCM measures the voltage changes in the signal due to the sensors resistance. A high air temperature will result in low resistance (near 0 volt) at the PCM and low air temperature will result in high signal voltage (near 5 volt).