P0112

Diagnostic Chart:

Wiring Chart:

CIRCUIT DESCRIPTION

The Intake Air Temperature (IAT) sensor is a thermister 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 SETTING THE DTC

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

^ The intake air temperature is greater than or equal to 151°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 will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle).

^ Use of a Scan Tool will clear the DTC codes.


DIAGNOSTIC AIDS

Check harness routing for a potential short to ground in the signal circuit. Scan Tool displays intake air temperature in degrees centigrade. Refer to Symptoms. Testing and Inspection

A skewed sensor could result in poor driveability complaints. Refer to Specifications / Electrical / 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 it the PCM can recognized 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.