P0112

DTC P0112

CIRCUIT DESCRIPTION
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The IAT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 voltsto the IAT signal circuit and a ground for the IAT low reference circuit. If the ECM detects an excessively low IAT signal voltage, which is a high temperature indication, this DTC sets.




The table illustrates the difference between temperature, resistance, and voltage:

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0112 Intake Air Temperature (IAT) Sensor Circuit Low Voltage

CONDITIONS FOR RUNNING THE DTC
- DTC P0502 is not set.
- The engine run time is more than 120 seconds.
- The vehicle speed is more than 50 km/h (31 mph).
- This DTC runs continuously once the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The ECM detects that the IAT sensor is more than 149°C (300°F) for more than 10 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
- Test the IAT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a driveability condition.
- If the vehicle has set overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F). Refer to Temperature vs Resistance.
- A high resistance on either the IAT sensor signal circuit or the IAT sensor low reference circuit may not set a DTC.
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

TEST

Steps 1-4:

Steps 5-11: