P0112

DTC P0112 or P0113

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0112
- Intake Air Temperature (IAT) Sensor Circuit Low Voltage

DTC P0113
- Intake Air Temperature (IAT) Sensor Circuit High Voltage

Diagnostic Fault Information

Typical Scan Tool Data

Circuit/System Description

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The control module supplies 5 volts to the IAT signal circuit, and a ground for the IAT low reference circuit.

Conditions for Running the DTC

P0112
* DTCs P0116, P0117, P0118, P0502 (if applicable), P0503 (if applicable), P0608, P0609 are not set.
* The engine run time is more than 10 seconds.
* The vehicle speed sensor (VSS) indicates that vehicle speed is more than 40 km/h (25 mph).
* The engine coolant temperature (ECT) is less than 123°C (253°F).
* This diagnostic runs continuously when the above conditions are met.

P0113
* DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0502 (if applicable), P0503 (if applicable), P0608, P0609 are not set.
* The engine run time is more than 180 seconds.
* The VSS indicates that vehicle speed is less than 24 km/h (15 mph).
* The mass air flow (MAF) is less than 10 g/s.
* The ECT is more than 60°C (140°F).

Conditions for Setting the DTC

P0112

The control module detects that the IAT sensor parameter is more than 130°C (266°F) for more than 18 seconds.

P0113

The control module detects that the IAT sensor parameter is less than -36°C (-33°F) for more than 110 seconds.

Action Taken When the DTC Sets

DTC P0112 and P0113 are Type B DTCs.

Conditions for Clearing the DTC

DTC P0112 and P0113 are Type B DTCs.

Diagnostic Aids

* Ignition ON, if the engine is cold, a properly functioning IAT sensor will gradually increase the scan tool IAT Sensor parameter. This is due to the heat that is generated by the mass air flow (MAF) sensor heating elements.
* Depending on the ambient temperature, an IAT sensor signal circuit or low reference circuit that is shorted to the MAF sensor signal circuit can cause a DTC P0113 to set. This condition causes a rapid fluctuation in the IAT Sensor parameter.
* An IAT sensor signal circuit that is shorted to the MAF sensor ignition circuit can cause a DTC P0113 to set.

Circuit/System Verification

* If the ignition has been OFF for 8 hours or greater, the IAT and the ECT should be within 15°C (27°F) of each other and also the ambient temperature. Ignition ON, observe the scan tool Start-up ECT and Start-up IAT Sensor parameters. Compare those sensor parameters to each other and also to the ambient temperature to determine if the IAT sensor is within an acceptable operating range.
* Engine running, observe the scan tool IAT Sensor parameter. The reading should be between -39 to +120°C (-38 to +248°F) depending on the current ambient temperature and the vehicle operating conditions.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the IAT sensor.
2. Ignition OFF for 90 seconds, test for less than 5 ohm of resistance between the low reference circuit terminal E and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the engine control module (ECM).

3. Ignition ON, verify the scan tool IAT parameter is less than -39°C (-38°F).

• If greater than the specified range, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the ECM.

4. Install a 3A fused jumper wire between the signal circuit terminal D and a good ground. Verify the scan tool IAT parameter is greater than 149°C (300°F).

• If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the IAT sensor.

Component Testing

Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the Temperature Vs Resistance table.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

* Mass Airflow Sensor/Intake Air Temperature Sensor Replacement
* Control Module References Programming and Relearning Verification Tests