P1111

Circuit Description
The intake air temperature (IAT) sensor is a thermistor that measures the temperature of the air entering the engine. The powertrain control module (PCM) applies 5 volts to the IAT sensor through a pull-up resistor. When the intake air is cold, the sensor resistance is high and the PCM monitors a high signal voltage on the IAT signal circuit. If the intake air is warm, the sensor resistance is lower causing the PCM to monitor a lower voltage. DTC P1111 is set when the PCM detects an intermittently high signal voltage on the IAT sensor signal circuit.

Conditions for Running the DTC
1. No engine coolant temperature (ECT) sensor, mass air flow (MAF) sensor or vehicle speed sensor (VSS) DTCs are present
2. The engine is running for over 3 minutes.
3. The ECT is more than 60°C (140°F).
4. The vehicle speed is less than 35 mph.

Conditions for Setting the DTC
The IAT signal voltage intermittently indicates an IAT of less than -34°C (-29°F).

Action Taken When the DTC Sets
The PCM stores the conditions which were present when the DTC set as Fail Records data only.

Conditions for Clearing the MIL/DTC
^ A history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
^ DTC may be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids
Inspect for the following conditions:
^ A faulty connection at the PCM or the IAT sensor. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections.
^ Inspect the wiring harness for damage. If the harness appears to be OK, observe the IAT display on a scan tool while moving the connectors and wiring harnesses related to the IAT sensor. A change in the IAT display indicates the location of the malfunction.
^ A skewed or mis-scaled IAT sensor.

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