P0111
DTC P0111
DTC Descriptor
DTC P0111
- Intake Air Temperature (IAT) Sensor 1 Performance
Circuit Description
The mass air flow (MAF) and the intake air temperature (IAT) sensor 1 are an integrated sensor. The IAT sensor 1 is a variable resistor that measures the temperature of the air entering the induction system. The powertrain control module (PCM) supplies 5 volts to the IAT sensor 1 signal circuit and a ground for the IAT sensor 1 low reference circuit. When the sensor is cold, the resistance is greater. This results in a greater voltage on the signal circuit that is interpreted by the PCM as a colder IAT. As the sensor becomes warmer, the resistance decreases. This results in a lesser voltage on the IAT signal circuit that is interpreted by the PCM as a warmer IAT. If the PCM detects an IAT sensor 1 signal voltage that is not within a calibrated range of the IAT sensor 2 signal voltage, DTC P0111 sets.
Conditions for Running the DTC
* DTCs P0096, P0097, P0098, P0112, P0113, P0116, P0117 P0118, P0125, P0128 are not set.
* DTC P0116 must run and pass.
* The ignition OFF time is greater than 8 hours.
* The ignition is ON for the initial power-up comparison.
* This DTC runs once per ignition cycle within the enabling conditions.
Conditions for Setting the DTC
The PCM detects that the IAT sensor 1 parameter is not within 16°C (29°F) of the IAT Sensor 2 parameter.
Action Taken When the DTC Sets
* The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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
Important: Determine the ambient temperature by using an accurate thermometer.
* If the ignition has been OFF for 8 hours or more, the IAT Sensor 1 parameter, the IAT Sensor 2 parameter and the ECT Sensor parameter should be within 15°C (27°F) of each other and also the ambient temperature. Turn ON the ignition, and immediately observe the parameters. Compare those sensor parameters to each other and also to the ambient temperature, to determine if the IAT Sensor 1 parameter is skewed.
* If the engine is cold, then at ignition ON, a properly functioning IAT sensor 1 will gradually increase the scan tool IAT Sensor 1 parameter. This is due to the heat that is generated by the MAF sensor heating elements.
* With the engine running, and depending on the ambient temperature, an IAT sensor 1 signal circuit that is shorted to the MAF sensor signal circuit can cause a rapid fluctuation in the IAT Sensor 1 parameter and can cause DTC P0111 to set.
Test
