P1112
DTC P1112CIRCUIT 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 intermittent 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 supports the following DTC:
DTC P1112 Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage
CONDITIONS FOR RUNNING THE DTC
- DTC P0502 is not set.
- The vehicle speed is more than 50 km/h (31 mph).
- The engine run time is more than 120 seconds.
- This DTC runs continuously when the above conditions are met.
CONDITIONS FOR SETTING THE DTC
- The ECM detects that the intake air temperature (IAT) is more than 149°C (300°F) intermittently.
- The condition exists for more than 20 seconds.
ACTION TAKEN WHEN THE DTC SETS
- The control module stores the DTC information into memory when the diagnostic runs and fails.
- The malfunction indicator lamp (MIL) will not illuminate.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
- The driver information center, if equipped, may display a message.
CONDITIONS FOR CLEARING THE DTC
- 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 non-emission related diagnostic.
- Clear the DTC with a scan tool.
DIAGNOSTIC AIDS
- Test the ECT 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.
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions
TEST
