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.
- Detach the air flow sensor electrical connector.
- Measure the resistance between terminals No. 4 and No. 6 of the electrical connector, except on the 2.0L DOHC turbo engine.
- If equipped with the 2.0L DOHC turbo engine, measure the resistance between terminals No. 6 and No. 8 of the sensor electric connector.
- Compare test readings to the following specifications:
- Sensor temperature of 32°F (0°C)-5.3-6.7 kilo-ohms
- Sensor temperature of 68°F (20°C)-2.3-3.0 kilo-ohms
- Sensor temperature of 176°F (80°C)-0.30-0.42 kilo-ohms
- Measure the sensor resistance while heating the sensor area with a hair dryer. As the temperature of the sensor increases, sensor resistance should become smaller.
- If the measured resistance deviates from the standard value or the resistance remains unchanged, replace the air flow sensor assembly.
REMOVAL & INSTALLATION
The IAT sensor is part of the Mass Air Flow (MAF) sensor. The IAT sensor cannot be replaced separately. Refer to MAF sensor removal and installation in this section.