P1111

DTC P1111 IAT Sensor CKT Intermittent High Voltage:

IAT Sensor Circuit:

CIRCUIT DESCRIPTION

The Intake Air Temperature (IAT) sensor is a thermistor which measures the temperature of the air entering the engine. The PCM applies 5 volts through a pull-up resistor to the IAT sensor. When the intake air is cold, the sensor resistance is high and the PCM will monitor a high signal voltage on the IAT signal circuit. lithe intake air is warm, the sensor resistance is lower causing the PCM to monitor a lower voltage. DTC P1111 will set when the PCM detects an intermittently high signal voltage on the intake air temperature sensor signal circuit.


CONDITIONS FOR SETTING THE DTC

^ No Engine Coolant Temperature (ECT) sensor, Mass Air Flow (MAF) sensor or Vehicle Speed Sensor (VSS) DTCs present.

^ The engine has been running for over 3 minutes.

^ Engine coolant temperature is greater than 6O°C (14O°F).

^ Vehicle speed is less than 56 km/h (35 mph).

^ IAT signal voltage intermittently indicates an intake air temperature less than -39°C (-38°F).


ACTION TAKEN WHEN THE DTC SETS

^ The PCM wilt not illuminate the Malfunction Indicator Lamp (MIL).

^ The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.


CONDITIONS FOR CLEARING THE MIL/DTC

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

^ DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.


DIAGNOSTIC AIDS

Check for the following conditions:

^ Poor connection at the PCM.

Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

^ Damaged harness. Inspect the wiring harness for damage.

^ If the harness appears to be OK, observe the IAT display on the scan tool while moving connectors and wiring harnesses related to the IAT sensor. A change in the IAT display will indicate the location of the fault.

^ Skewed or mis-scaled IAT Sensor. Refer to Temperature vs Resistance table. Specifications

Reviewing the Fail Records vehicle mileage since the diagnostic test last tailed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.