P0112

DTC P0112 or P0113

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide 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 1 is a variable resistor. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT signal circuit, and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT signal circuit.

Conditions for Running the DTC

* The engine is running.
* DTC P0112 and P0113 run continuously.

Conditions for Setting the DTC

P0112

The IAT Sensor parameter is greater than 148°C (299°F) for greater than 1 second. This is equal to or less than 0.10 volt on the IAT signal circuit as measured by the ECM.

P0113

The IAT Sensor parameter is less than -39°C (-38°F) for greater than 1 second. This is equal to greater than 4.8 volts on the IAT signal circuit as measured by the ECM.

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

* If the engine is cold and the ignition is turned ON, a properly functioning IAT sensor will gradually increment to a higher value. This is due to the heat that is generated by the MAF sensor heating elements.
* Depending on the ambient temperature, an IAT sensor signal circuit is shorted to the MAF sensor signal circuit can cause a DTC P0113 to set.
* An IAT sensor signal circuit that is shorted to the MAF sensor ignition circuit can cause a DTC P0113 to set.
* Verify that any electrical aftermarket devices are properly connected and grounded. Refer to Checking Aftermarket Accessories in Diagnostic Aids. Component Tests and General Diagnostics

Circuit/System Verification

* Engine running, observe the scan tool IAT Sensor 1 parameter. The reading should be between -39°C to +120°C (-38°F to +248°F) depending on the current ambient temperature and the vehicle operating conditions.
* Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the mass air flow MAF/IAT sensor.
2. Ignition OFF, for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal 4 and ground.

• If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify the scan tool IAT Sensor 1 parameter is less than -39°C (-38°F).

• If greater than the specified value, test the signal circuit terminal 5 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 5 and a ground. Verify the scan tool IAT Sensor 1 parameter is greater than 149°C (300°F).

• If less than the specified value, 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 IAT sensor 1.

Component Testing

1. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
2. Measure and record the resistance between the signal terminal 5 and the low reference circuit terminal 4 at the IAT sensor. Compare the value to the Temperature Vs Resistance table. Refer to Temperature Versus Resistance (Exhaust Gas Temperature Sensor) Temperature Versus Resistance (Fuel Temperature Sensor) Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (IAT Sensor 2).

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Mass Airflow Sensor/Intake Air Temperature Sensor Replacement
* Control Module References for ECM replacement, setup, and programming Programming and Relearning Verification Tests