P0112

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The Intake Air Temperature (IAT) sensor is a thermister that controls 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 air warms, sensor resistance becomes less and voltage drops.

Conditions for Setting the DTC

^ The PCM performs this DTC diagnostic continuously.

^ The engine coolant temperature is less than 42.5°C (109°F).

^ The Intake air temperature is greater than or equal to 151°C (303°F).

^ All of the diagnostic set conditions met for 2 seconds.

Action Taken When the DTC Sets

^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and tails.

^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records will 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 will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F)) that same ignition cycle.

^ Use of a Scan Tool

Diagnostic Aids

Check harness routing for a potential short to ground in the signal circuit. Refer to Symptoms. Testing and Inspection

The scan tool displays intake air temperature in degrees centigrade. A skewed sensor could result in poor driveability complaints. Refer to Temperature vs Resistance.

Test Description

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 recognized an open sensor.

4. This step will determine if the problem is a short to ground or a malfunctioning PCM.