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 |
|---|---|---|---|---|
IAT Sensor Signal | P0112 | P0113 | P0113 | P0113 |
IAT Low Reference | -- | P0113 | P0113 | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open or High Resistance | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine Running Parameter Normal Range: Varies between -39 to +120°C (-38 to +248°F) | |||
IAT Sensor Signal | 149°C (300°F) | -40°C (-40°F) | -40°C (-40°F) |
IAT Low Reference | -- | -40°C (-40°F) | -- |
Circuit/System Description
The intake air temperature (IAT) sensor 1 is a variable resistor. The IAT sensor 1 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 1 parameter is greater than 148°C (299°F) for more 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 1 parameter is less than -39°C (-38°F) for more than 1 second. This is equal to or more than 4.8 volts on the IAT signal circuit as measured by the ECM.
Action Taken When the DTC Sets
DTCs P0112 and P0113 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs 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 1 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 1 signal circuit or low reference circuit that is shorted to the MAF sensor signal circuit can cause a DTC P0113 to set. |
| • | An IAT sensor 1 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 . |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Scan Tool Reference
Circuit/System Verification
Important: Perform this verification procedure only if the ignition has been OFF for 8 hours or more.
- 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.
- Engine running, observe the DTC information with a scan tool. DTCs P0112 or P0113 should not set.
- 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/Failure Records data.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the mass air flow (MAF)/IAT sensor.
- Ignition OFF and scan tool disconnected for 90 seconds, test for less than 5 ohms of between the low reference circuit terminal 1 and ground.
- Ignition ON, verify the scan tool IAT Sensor 1 parameter is less than -39°C (-38°F).
- Install a 3A fused jumper wire between the signal circuit terminal 2 and a ground. Verify the scan tool IAT Sensor 1 parameter is greater than 149°C (300°F).
- If all circuits test normal, test the MAF/IAT sensor.
| ⇒ | If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the ECM. |
Important: If a short to voltage is found on the IAT signal circuit, the 3A fuse in the jumper wire will open.
| ⇒ | 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. |
Component Testing
| • | Ignition OFF, disconnect the harness connector at the MAF/IAT sensor. |
| • | Measure the resistance between the signal terminal 2 and the low reference circuit terminal 1 at the sensor. Compare the value to the Temperature Vs Resistance table. Verify the resistance is within 5 percent of the specification. 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 |
