P1111

DTC P1111

Circuit Description

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an excessively high IAT signal voltage, indicating a low temperature, DTC P1111 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1111 Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage

Conditions for Running the DTC

* DTCs P0101, P0102, P0103, P0117, P0118, P0502, and P0503 are not set.
* The engine run time is more than 10 seconds.
* The vehicle speed sensor (VSS) indicates that vehicle speed is less than 1.6 km/h (1 mph).
* The engine coolant temperature (ECT) is more than 50°C (122°F).
* The mass air flow (MAF) is less than 12 g/s.
* DTC P1111 runs continuously when the above conditions are met.

Conditions for Setting the DTC

The PCM detects that the IAT sensor parameter is less than -39°C (-38°F) intermittently for more than 30 seconds.

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.
* Clear the DTC with a scan tool.

Test Description

Step 1 - Step 10:

Step 11 - Step 16:

The number below refers to the step number on the diagnostic table.
6. This step tests for the proper operation of the circuit in the low voltage range.