P0112

Circuit Description
The Intake Air Temperature (IAT) sensor is a thermistor that controls the signal voltage to the PCM. When the air is cold, the sensor resistance is high, therefore the PCM will see a high signal voltage. As the air warms, the sensor resistance becomes less and the voltage drops.

Conditions for Running the DTC
The Engine Coolant Temperature is less than 42.5°C (109°F).

Conditions for Setting the DTC
^ The intake air temperature is greater than or equal to 152°C (304°F).
^ The conditions were met for 2 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records.

Conditions for Clearing the MIL/DTC
^ The PCM will turn the MIL off after three consecutive trips without a fault condition.
^ A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures
^ The use of a scan tool.

Diagnostic Aids
Check harness routing for a potential short to ground in the signal circuit. Scan tool displays intake air temperature in degrees Celsius. Refer to Symptoms. A skewed sensor could result in poor driveability complaints. Refer to Temperature vs Resistance.

Test Description
The number(s) below refer to the step number(s) on the Diagnostic Table.
2. This step determines if P0112 is a hard failure or an intermittent condition.
3. This test will determine if the PCM can recognize an open sensor.
4. This step will determine if the problem is a malfunctioning PCM or the signal wire is shorted to ground. The normal resistance across the IAT sensor connector harness is 4000-5000 ohms.