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
- Disconnect the electrical connector as shown (1) for the mass air flow (MAF)/air intake temperature (IAT) sensor (5).
- Remove the lines (2) from the air duct (4).
- Loosen the air intake duct clamps (3).
- Remove the air intake duct (4) from the throttle body.
Remove the MAF/IAT sensor (5) from the air cleaner housing.
- Disconnect the mass air flow (MAF)/air intake temperature (IAT) sensor electrical connector.
- Remove the 2 screws and the MAF/IAT sensor from the air cleaner housing.
Installation is the reverse of removal.
Off Vehicle Testing
- 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.
-4°F: 28680 ohms
- If the sensor tests outside of these ranges, replace the sensor
- Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
Ignition ON, verify the scan tool IAT Sensor parameter is less than -39°C (-38°F).
- If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
Install a 3A fused jumper wire between the signal circuit and a good ground. Verify the scan tool IAT Sensor parameter is greater than 149°C (300°F).
- If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance.
- If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the MAF/IAT sensor.