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

Notice: A short to B+ on signal circuit 472 may damage the IAT sensor. Check for correct resistance vs. temperature of the sensor after repair has been made.

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

DTC P0113 will set if the IAT reading is lower than -30°C (-22°F) when:

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

• | Vehicle speed is less than 24 km/h (15 mph).

• | No VSS DTC has been set.

• | Airflow is less than 16 gm/sec.

DTC P0113 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.

• | This DTC may be set if the vehicle has been in extremely cold ambients -37°C (-35°F). Ask the customer if this has occurred.

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