Circuit Description
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 air induction temperature. The ECM supplies a five volt reference through a pull-up resistor to the sensor, which is connected to ground. When the sensor is cold it has high resistance (high signal voltage at ECM). As the sensor temperature increases, its resistance decreases (low signal voltage at ECM). The ECM uses the signal voltage to determine 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 IAT temperature is over 139°C (282°F) when:
| • | Condition exists for longer than 2 seconds. |
| • | Engine run time is greater than 1 minute and 20 seconds. |
| • | 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 Scan tool to monitor IAT temperature with ignition On, engine Off. Wiggling wires while watching for a change in IAT temperature may locate the area where a short to ground in the wiring could lie.
Refer to ECT General Description for a Temperature vs. Resistance chart.
