Intake Air Temperature (IAT) Sensor

The IAT sensor is a thermistor (a resistor which changes value based on temperature) mounted inside of intake manifold and measures air temperature entering engine. At cold air temperatures, IAT sensor resistance is high and at hot air temperatures, resistance of sensor is low. The PCM supplies a 5 volt reference signal and a ground to sensor and measures voltage signal as it is changed by sensor. The voltage is close to 5 volts at cold temperatures and close to zero volts at hot temperatures. See Figure and Figure .

The PCM uses IAT information in conjunction with MAP information to determine density of air entering engine. A faulty IAT sensor may cause various driveability conditions and should set a PCM Trouble Code.