P0111

DTC P0111 Intake Air Temperature (IAT) Sensor Rationality Check

Circuit Description

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

Conditions for Setting the DTC

- Vehicle speed is higher than 5 km/h (3.1 mph) during 12 seconds.
- 300 seconds after starting the engine.
- Vehicle is driven longer than 7 km (4.4 miles).
- Coolant temperature is higher than 80.25 °C (176.45 °F).
- Coolant temperature deviation is greater than 40 °C (104 °F).
- The IAT sensor signal indicates a smaller change in the voltage than expected.

Action Taken When the DTC Sets

- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fail. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC

- The MIL will turn off at the end of three (3) consecutive validation cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 warm up cycles without a fault.
- DTC(s) can be cleared by using the scan tool.

Diagnostic Aids

Check for a faulty electrical connection to the ECM. If the vehicle is at ambient temperature, compare the IAT sensor to the engine coolant temperature (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. Refer to Engine Controls Description.

Step 1 - 3:

Step 4 - 12:

DTC P0111 - Intake Air Temperature (IAT) Sensor Rationality Check