Air Temperature Sensor ( Ambient / Intake ): Testing and Inspection

A Tech 1 scan tool displays temperature of the air entering the engine and should read close to ambient air temperature when the engine is cold, and rise as underhood temperature increases. If the engine has not been run for several hours (overnight) the Intake Air Temperature (IAT) temperature and engine coolant temperature should read close to each other. A failure in the IAT sensor circuit should set a DTC 23 or 25. The DTC charts also contain a chart to check for sensor resistance values relative to temperature.