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

NOTE: Two separate intake air temperature sensors (IAT)s are utilized by the engine control system. One sensor is incorporated in the volume airflow sensor assembly and the other is mounted on the intake manifold dynamic chamber.

Volume Airflow Sensor IAT
The intake air temperature sensor is a negative temperature coefficient thermistor. Negative temperature coefficient means as temperature increases, resistance decreases. Cold air is more dense than warm air. The powertrain control module (PCME) measures the resistance of the intake air temperature sensor, calculates the temperature of the incoming air, and uses this information to help regulate the following:

- Fuel injection quantity
- Idle speed control
- Vapor canister purge control

Sensor resistance is checked at volume airflow sensor terminals "E2" and "THA".

Dynamic Chamber IAT
The IAT, installed in the right front corner of the intake manifold dynamic chamber (from underneath), detects intake air temperature. The PCME uses this information to help regulate the following:

- Fuel injection quantity
- Ignition timing control