Scan Tool Testing and Procedures

SCAN TOOL TESTING
The Tech 1 scan tool (or equivalent) displays temperature of the air entering the engine and should be 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 (overnight) the Intake Air Temperature (IAT) sensor temperature and Engine Coolant Temperature (ECT) sensors should display temperature readings close to each other.

CIRCUIT FAILURE
A failure in the IAT sensor circuit should set either:

Code 23 Intake Air Temperature Sensor (Low Temp Indicated) Powertrain Controls - ECM/PCM

OR

Code 25 Intake Air Temp (IAT) Sensor (High Temp Indicated) Powertrain Controls - ECM/PCM