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 provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0112: Intake Air Temperature (IAT) Sensor Circuit Low VoltageDTC P0113: Intake Air Temperature (IAT) Sensor Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
IAT Sensor Signal | P0112 | P0113 | P0113 | P0113 | -- |
Low Reference | -- | P0113 | P0113 | P0113 | -- |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
IAT Sensor Signal | -39 to +120°C (-38 to +248°F) | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -- | -40°C (-40°F) | -40°C (-40°F) |
Circuit/System Description
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT sensor signal circuit and supplies a ground to the low reference circuit.
Conditions for Running the DTC
P0112
| • | DTCs P0116, P0117, P0118, P0128, P0502, P0503 are not set. |
| • | The engine is running for greater than 10 seconds. |
| • | The engine coolant temperature (ECT) is less than 150°C (302°F). |
| • | This DTC runs continuously within the enabling conditions. |
P0113
| • | DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0128, P0502, P0503 are not set. |
| • | The engine is running for greater than 10 seconds. |
| • | The ECT is greater than -40°C (-40°F). |
| • | This DTC runs continuously within the enabling conditions. |
Conditions for Setting the DTC
P0112
The ECM detects that the IAT is greater than 149°C (300°F) for greater than 5 seconds.
P0113
The ECM detects that the IAT is less than -39°C (-38°F) for greater than 5 seconds.
Action Taken When the DTC Sets
| • | DTC P0112 is a Type B DTC. |
| • | DTC P0113 is a Type B DTC. |
Conditions for Clearing the MIL/DTC
| • | DTC P0112 is a Type B DTC. |
| • | DTC P0113 is a Type B DTC. |
Diagnostic Aids
| • | If the engine is cold, then at ignition ON, 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 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. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
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
Important: All electrical components and accessories must be turned OFF and allowed to power down.
- Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
- Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal D and ground.
- Ignition ON, verify the scan tool IAT Sensor parameter is less than -39°C (-38°F).
- Install a 3A fused jumper wire between the signal circuit terminal E and a good ground. Verify the scan tool IAT Sensor parameter is greater than 149°C (300°F).
- If the circuits test normal, test the IAT sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | 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. |
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. Refer to Temperature Versus Resistance .
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
