The intake air temperature sensor is an integral part of the mass air flow sensor (MAF). The intake air temperature (IAT) sensor is a thermistor that varies resistance according to changes in the air induction temperature. The ECM supplies a 5-volt reference through a pull-up resistor to the sensor, which is connected to a ground. When the sensor is cold it has high resistance (high signal voltage at the ECM). As the sensor temperature increases, its resistance decreases (lower signal voltage at the ECM). The ECM uses the signal voltage to determine the air induction temperature. DTC P0112 sets when the IAT sensor signal voltage at the ECM is below the calibrated voltage value (over the calibrated temperature value).
DTC Parameters
DTC P0112 will set if the IAT sensor temperature is over 139°C (282°F) when:
| • | The condition exists for longer than 2 seconds. |
| • | The engine run time is greater than 1 minute and 20 seconds. |
| • | The engine has been at idle for at least 10 seconds. |
DTC P0112 diagnostic runs continuously once the above conditions have been met.
P0112 is a type B DTC.
Diagnostic Aids
To locate an intermittent problem, use the scan tool to monitor the IAT temperature with the ignition On, and the engine Off. Wiggling the wires while watching for a change in the IAT temperature may locate the area where a short to ground in the wiring could lie.
Refer to the ECT General Description for the Temperature vs. Resistance chart.
