Intake Air Temperature (IAT) Sensor (Some Engines)

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.

IAT sensor is a thermistor (temperature sensitive resistor) mounted in the intake manifold. Low intake air temperature produces high internal sensor resistance, while high temperature causes low internal sensor resistance. The PCM supplies and monitors a 5-volt signal to sensor through a pull-down resistor in PCM.

IAT sensor, also known as an manifold air temperature sensor, allows PCM to determine intake air temperature. PCM uses signal to delay EGR until intake air temperature reaches about 40°F (5°C). If intake air temperature becomes excessively high, PCM compensates by slightly retarding ignition timing. After a vehicle has sat overnight, IAT and CTS signals (resistance and temperature) should be close to same reading. Failure in IAT sensor circuit should set a related trouble code.