Intake Air Temperature Sensor

The Intake Air Temperature (IAT) sensor is a thermistor. a resistor which changes value based on temperature of air entering engine. Low temperature produces a high resistance (4,500 ohms at -40° F [-40° C]), while high temperature causes a low resistance (70 ohms at 266° F [130° C]).

The powertrain control module (PCM)/engine control module (ECM) provides 5 volts to IAT sensor through a resistor in PCM/ECM and measures change in voltage to determine IAT. The voltage will be high when manifold air is cold and low when air is hot. The PCM/ECM knows intake IAT by measuring voltage.

The IAT sensor is also used to control spark timing when manifold air is cold. A failure in IAT sensor circuit sets a diagnostic trouble code P0112 or P0113.