P0112

DTC P0112 IAT Sensor Circuit Low Voltage (b)






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 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 151°C (304°F).
^ All 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 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, if this or any other emission related diagnostic does not report any failures.
^ 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. 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.