Circuit Description
The intake air temperature sensor is a thermistor (a variable resistor) that measures the temperature of the air entering the engine. The PCM supplies 5 volts to the IAT signal circuit through a pull-up resistor. When the intake air is cold, the PCM detects a high voltage on the IAT signal circuit. As the intake air warms, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an intermittently low IAT signal voltage (high temperature indicated), DTC P0112 will set.
Conditions for Running the DTC
| • | ECT sensor, MAF sensor, or VSS DTCs are not set |
| • | The engine coolant temperature is less than 100°C (212°F). |
| • | The vehicle speed is more than 15 km/h (9 mph). |
Conditions for Setting the DTC
| • | The IAT sensor signal voltage is less than 0.25 volts. This would be approximately 133°C (271°F). |
| • | The condition exists for less than 1 second. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) the first time the malfunction is detected. |
| • | The PCM will store the conditions present when the DTC set as Freeze Frame and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic runs and passes. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions .
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||||||
2 | Are any other DTCs also set? | -- | Go to the other DTCs first | |||||
3 |
Did you find and correct the condition? | -- | Go to Diagnostic Aids | |||||
4 |
Does the scan tool indicate that DTC P1112 passed? | -- | System OK |
