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. |
