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

Fig. 11 Intake Air Temperature Sensor And MAP Sensor:

PURPOSE
The PCM uses this signal to compensate for changes in air density due to temperature.

OPERATION
The intake air temperature sensor (IAT) is located in the intake manifold where it measures the temperature of the air that is about to enter the combustion chambers. The IAT is a negative temperature coefficient (NTC) thermistor-type sensor (resistance varies inversely with temperature). This means at cold temperatures its resistance is high so the voltage signal will be high. At high temperatures, resistance decreases and the voltage will decrease. This allows the sensor to provide an analog voltage signal to PCM cavity 6.

NAME OF CODE: Intake Air Temp Sensor Voltage High

When Monitored:
With the ignition ON and the engine running.

Set Condition:
The intake air sensor circuit voltage at Powertrain Control Module (PCM) cavity 6 goes above 4.9 volts.


Possible Causes:
- Sensor signal circuit open
- Sensor internally open
- Sensor ground circuit open
- Powertrain control module failure

NAME OF CODE: Intake Air Temp Sensor Voltage Low

When Monitored:
With the ignition ON and the engine running.

Set Condition:
The intake air sensor circuit voltage at Powertrain Control Module (PCM) cavity 6 goes below 0.157 volt.

Possible Causes:
- Sensor signal circuit shorted to ground
- Sensor internally shorted
- Powertrain control module failure