The IAT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to temperature. Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.
The IAT provides air temperature information to the PCM. The PCM uses the air temperature information as a correction factor in the calculation of fuel, spark, and air flow. The IAT sensor provides a quicker temperature change response time than the ECT or CHT sensor. Currently there are 2 design types of IAT sensors used, a stand alone/non-integrated type and a integrated type. Both types function the same, however the integrated type is incorporated into the mass air flow (MAF) sensor instead of being a stand alone sensor.
Supercharged vehicles use 2 IAT sensors. Both sensors are thermistor type devices and operate as described above. One is located before the supercharger at the air cleaner for standard OBD/cold weather input, while a second sensor (IAT2) is located after the supercharger in the intake manifold. The IAT2 sensor located after the supercharger provides air temperature information to the PCM to control spark and to help determine Charge Air Cooler (CAC) efficiency.
Removal & Installation
- Disconnect the Intake Air Temperature 2 (IAT2) sensor electrical connector.
- Remove the IAT2 sensor.
Install the IAT2 sensor. Tighten the IAT2 sensor in 2 stages:
Stage 1: Tighten the IAT2 sensor to 11 ft. lbs. (15 Nm).
NOTEDuring Stage 2, do not tighten the IAT2 sensor more than one full turn and do not rotate the IAT2 sensor counter clockwise after tightening.
- Stage 2: Tighten the IAT2 sensor until it is aligned as shown.
- Stage 1: Tighten the IAT2 sensor to 11 ft. lbs. (15 Nm).
- Connect the IAT2 sensor electrical connector.
IAT Sensor Pin Testing
This pinpoint test is intended to diagnose the following:
Voltage values calculated for VREF = 5 volts. These values can vary by 15% due to sensor and VREF variations.