P1112

CIRCUIT DESCRIPTION
The Intake Air Temperature (IAT) sensor contains a semiconductor device which changes the resistance based on the temperature. The IAT sensor is located within the Mass Air Flow (MAF) sensor. The IAT sensor has a signal circuit and a ground circuit. The Powertrain Control Module (PCM) applies 5 volts on the signal circuit to the sensor. The PCM monitors the changes in this voltage caused by changes in the resistance of the sensor in order to determine intake air temperature.

When the intake air is cold, the sensor resistance is high. The PCM signal voltage is only pulled down a small amount through the sensor to a ground. Therefore, the PCM senses a high signal voltage. When the intake air is warm, the sensor resistance is low. The signal voltage is pulled down a greater amount; therefore, the PCM senses a low signal voltage.

When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC sets.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0502 and DTC P0503 are not set.
^ The vehicle speed is more than 2 km/h (3 mph).
^ The engine run time is greater than 100 seconds.

CONDITIONS FOR SETTING THE DTC
The PCM detects an intermittent low IAT voltage while the engine is running and the vehicle exceeds 2 km/h (3 mph).

ACTION TAKEN WHEN THE DTC SETS
^ The control module stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
^ The driver information center, if equipped, may display a message.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC Last Test Failed clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Use a scan tool in order to clear the DTC.

DIAGNOSTIC AIDS

IMPORTANT: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

If the engine is cold, the engine coolant temperature and the intake air temperature values should be within 3°C (37°F) of each other. If the temperatures are outside of this range, refer to Temperature vs Resistance. Temperature VS Resistance

For an intermittent,refer to Symptoms - Computers and Control Systems. Standard Model (Non-Alternative Fuels)

TEST

Steps 1-10: