Circuit Description
The intake air temperature (IAT) sensor is a thermistor which measures the temperature of the air entering the engine. The powertrain control module (PCM) applies 5 volts through a pull up resistor to the IAT sensor. When the intake air is cold, the sensor resistance is high and the PCM will monitor 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 P1112 will set when the PCM detects an intermittently low signal voltage on the intake air temperature sensor signal circuit.
Conditions for Running the DTC
| • | DTC's P0101, P0102, P0103, P0117, P0118, P0125, P0128, P0502, P0503, P1114 and P1115 are not set. |
| • | The engine has been running for over 10 seconds. |
| • | The vehicle speed is more than 25 mph. |
Conditions for Setting the DTC
| • | The IAT sensor indicates an intake air temperature intermittently more than 135°C (275°F). |
| • | The conditions is present for up to 5 seconds. |
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 | With a scan tool, select diagnostic trouble codes (DTC). Does the scan tool indicate DTC P0112 also set? | Go to DTC P0112 | Go to Step 3 |
3 | Test the signal circuit for an intermittent short to ground. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 4 | Go to Intermittent Conditions |
4 |
Does the DTC set? | Go to Step 2 | System OK |
