For 1990-2009 cars

### Circuit Description

The intake air temperature (IAT) sensor is a thermistor located in the air intake passage of the air induction system on the engine. When the sensor is cold, it has a high resistance. The resistance decreases as the temperature of the sensor increases. The PCM supplies a 5 volt signal to the sensor which is also connected to ground. The PCM reads the voltage drop on the sensor signal line to determine air temperature.

### Conditions for Setting the DTC

Important: The IAT signal is continuously checked when the ignition is ON.

DTC P0112 will set if the IAT reading is over 125°C (257°F) when:

• | The engine run time is greater than 10 seconds.

• | VSS is present.

• | Air flow is less than 16 gm/second.

• | No VSS or ECT DTCs have been set.

DTC P0112 will set if conditions are met for about 6 seconds.

### Diagnostic Aids

Refer to description and operation in this manual for the Temperature vs. Resistance chart.

IAT temperature may be compared to ECT temperature with a scan tool if the engine has cooled overnight at ambient temperature. They should be within 4 degrees of each other with the ignition ON and the engine OFF.