P1112

Circuit Description

The Intake Air Temperature (IAT) sensor is a thermistor, or variable resistor, that varies resistance based on temperature. As the temperature of the sensor increases, resistance decreases. High temperature will result in a low signal voltage. DTC P1112 sets when the PCM sees an IAT sensor reading of 151°C (304°F) or more when the coolant is less than 110°C (230°F).

Conditions for Running the DTC

^ DTCs P0112, P0113, P0117 and P0118 not set.
^ ECT 110°C or less.
^ Vehicle speed 15 MPH or greater.

Conditions for Setting the DTC

IAT 151°C (304°F) or more.

Action Taken When the DTC Sets

^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ No message will be displayed.

Conditions for Clearing the DTC

^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
^ Use a scan tool to clear DTCs.
^ Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended.

Diagnostic Aids

DTC P1112 may set due to random engine backfires which could cause a sudden increase in intake temperature. Check if customer complained of this type of situation and make repairs if necessary.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

2. If DTC P0111 is also set, diagnose it first because it may help to pinpoint a faulty IAT sensor.
3. Checking for intermittent circuit faults that may cause a low IAT reading.