P0112

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The Intake Air Temperature (IAT) sensor uses a thermistor to control the signal voltage to the PCM. The PCM supplies a 5 V reference and a ground to the sensor. When the air is cold the resistance is high, therefore the IAT signal voltage will be high. If the intake air is warm, resistance is low, therefore the IAT signal voltage will be low.


CONDITIONS FOR SETTING THE DTC

^ Engine run time is greater than 320 seconds.

^ Vehicle speed is greater than 15 mph (24 km/h).

IAT is greater than 128°C (262°F).


ACTION TAKEN WHEN THE DTC SETS

^ The Malfunction Indicator Lamp (MIL) will illuminate.

^ The PCM will record operating conditions at the time the diagnostic tails. This information will be stored in the Freeze Frame and Failure Records buffers.

^ A history DTC is stored.

^ Coolant fan turns ON.

^ The PCM will default to 60°C (140°F) for intake air temperature. The scan tool will not the show the defaulted value.


CONDITIONS FOR CLEARING THE MIL/DTC

^ The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.

^ A history DTC will clear after 40 consecutive warm up cycles without a fault.

^ DTC(s) can be cleared by using the scan tool.

DIAGNOSTIC AIDS

^ If the vehicle is at ambient temperature, compare the IAT sensor to the ECT sensor. The IAT sensor and the ECT sensor should be relatively close to each other.

^ Use the Temperature vs. Resistance Values table to evaluate the possibility of a skewed sensor.


TEST DESCRIPTION

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

4. This step simulates a DTC P0113 condition. If the scan tool displays the specified value, the IAT signal circuit, the PCM are OK.

8. Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.