P0111

DTC P0111: Intake Air Temperature (IAT) Sensor Performance

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

(Condition 1)
- Engine is running.
- Intake air temperature is between -10.5 degrees C (13.1 degrees F) and 142.5 degrees C (288.5 degrees F).
- Engine coolant temperature is higher than -10.5 degrees C (13.1 degrees F).
- Engine is cold started.
- 700 seconds have been passed since starting.
- Vehicle has been driven for more than 7,000 m.
- IAT signal is less than 3 degrees C (37.4 degrees F) for more than 1 second.

(Condition 2)
- Engine coolant temperature is higher than -10.5 degrees C (13.1 degrees F).
- Mass air flow integral value is higher than threshold.
- IAT variation value is less than 3.75 degrees C (38.75 degrees F) or higher than 45 degrees C (113 degrees F).

(Condition 3)
- Engine coolant temperature is higher than -10.5 degrees C (13.1 degrees F).
- Mass air flow integral value is higher than threshold.
- IAT variation value is higher than -3.75 degrees C (25.25 degrees F).
- IAT variation value is higher than -35.25 degrees C (-31.45 degrees F).

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 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.

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DTC Troubleshooting