The Intake Air Temperature (IAT) sensor determines the air temperature entering the intake manifold. Resistance changes in response to the ambient air temperature. The sensor has a negative temperature coefficient. As the temperature of the sensor rises the resistance across the sensor decreases. This provides a signal to the PCM indicating the temperature of the incoming air charge. This sensor helps the PCM to determine spark timing and air/fuel ratio. Information from this sensor is added to the pressure sensor information to calculate the air mass being sent to the cylinders. The IAT receives a 5-volt reference signal and the signal return is based upon the change in the measured resistance due to temperature.
Removal & Installation
This procedure is for the intake manifold mounted IAT sensor on 6.6L engines. Refer to the MAF sensor removal and installation procedure for other IAT sensors.
- Remove the air intake pipe.
- Unplug the harness connector from the IAT sensor.
- Remove the sensor from the intake manifold.
Installation is the reverse of removal. Tighten the sensor to 18 ft. lbs. (25 Nm).
- Remove the IAT sensor.
- Measure and record the resistance of the IAT sensor at various temperatures, then compare those measurements to the following. The change in resistance should occur smoothly. If there are any sudden changes, the sensor is faulty.
Diesel engines; MAF mounted:
Diesel engines; manifold mounted:
- If the sensor tests outside of these ranges, replace the sensor.