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

Intake Air Temperature Sensor:

The Manifold Air Temperature (MAT) sensor is a thermistor whose resistance changes as a function of the temperature of air entering the engine. When the temperature is low, the resistance is high. Resistance decreases as the temperature increases. The MAT sensor is a two wire sensor that receives a 5.0 volt signal from the ECM through a resister in the ECM and measures voltage output. The voltage will be high when the incoming air is cold, and low when the air is hot.

Parameter ED23 displays temperature of the air entering the engine and should read close to ambient air temperature when engine is cold, and rise as underhood temperature increases. If the engine has not been run for several hours the MAT and coolant temperatures should read close to each other. A failure in the MAT sensor circuit should set a code E023 or E025.