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VIN 6




DTC P0112 or P0113

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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 that measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5V to the IAT signal circuit, and a ground for the IAT low reference circuit. The ECM continuously monitors the IAT sensor 1 signal voltage for an excessively high or low voltage.

Conditions for Running the DTC

* The engine is running.
* The DTCs run continuously when the above condition is met.

Conditions for Setting the DTC

P0112

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

P0113

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

Action Taken When the DTC Sets

* DTCs P0112 and P0113 are Type B DTCs.
* Diesel particulate filter (DPF) regeneration is inhibited.

Conditions for Clearing the DTC

DTCs P0112 and P0113 are Type B DTCs.

Diagnostic Aids

* With the ignition ON and the engine OFF, 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 can cause a rapid fluctuation in the IAT Sensor parameter.
* An IAT low reference circuit that is open can cause the IAT Sensor parameter response to be sluggish. This condition may not necessarily set a DTC.
* 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 (Checking Aftermarket Accessories).

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Note: Perform this verification procedure only if the ignition has been OFF for 8 hours or more.

1. Ignition ON, observe the scan tool IAT Sensor 1, IAT Sensor 2, and ECT Sensor parameters. The readings should be within 8°C (15°F) of each other and also the ambient temperature.
2. Engine idling, observe the scan tool IAT Sensor 1 parameter. The reading should be between -38 to +148°C (-36 to +298°F) depending on the current ambient temperature and the vehicle operating conditions.
3. Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the mass air flow MAF/IAT sensor.
2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohm between the IAT Sensor 1 low reference circuit terminal 4 and ground.

• If greater than the specified range, test the IAT Sensor 1 low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohm between the MAF sensor low reference circuit terminal 2 and ground.

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

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

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

Note: If a short to voltage is found on the IAT signal circuit, the 3A fuse in the jumper wire will open.

5. Install a 3A fused jumper wire between the IAT signal circuit terminal 5 and a ground. Verify the scan tool IAT Sensor 1 parameter is warmer than 148°C (298°F).

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

6. If all circuits test normal, test or replace the MAF/IAT sensor.

Component Testing

* Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
* Measure the resistance between the IAT signal terminal 5 and the IAT low reference circuit terminal 4 at the IAT sensor. Compare the value to the Temperature Vs Resistance table. Verify the resistance is within 5 % of the specification. Refer to Temperature Versus Resistance (Fuel Temperature Sensor) (Temperature Versus Resistance (Fuel Temperature Sensor)) Temperature Versus Resistance (ECT Sensors) (Temperature Versus Resistance (ECT Sensors)) Temperature Versus Resistance (IAT Sensor 1) (Temperature Versus Resistance (IAT Sensor 1)) Temperature Versus Resistance (IAT Sensor 2) (Temperature Versus Resistance (IAT Sensor 2)) Temperature Versus Resistance (EGT Sensors) (Temperature Versus Resistance (EGT Sensors)) Temperature Versus Resistance (EGR Temperature Sensors) (Temperature Versus Resistance (EGR Temperature Sensors)).

Repair Instructions

* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming

Repair Verification

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 90 seconds.
5. Duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) and perform the appropriate diagnostic procedure.
6. Perform the Diesel Particulate Filter (DPF) Service Regeneration (Diesel Particulate Filter (DPF) Service Regeneration).

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