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 | P0111, P0113 | P0113 | P0113 | P0111 |
Low Reference | -- | -- | -- | -- | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open or High Resistance | Short to Voltage |
|---|---|---|---|
Operating Conditions: The ignition is ON, with the engine OFF. Normal IAT Parameter: -39°C to +120°C (-38°F to +248°F) | |||
IAT Sensor Signal | 149°C (300°F) | -40°C (-40°F) | -40°C (-40°F |
IAT Low Reference | -- | -- | -- |
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 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
P0112
| • | DTC P0117, P0118, P0116, P0128, P0500, P0608, or P0609 are not set. |
| • | The engine speed is greater than 1 km/h (1 mph). |
| • | The engine coolant temperature (ECT) sensor is less than 150°C (302°F). |
| • | The engine run time is more than 10 seconds. |
| • | DTC P0112 runs continuously within the above enable conditions. |
P0113
| • | DTC P0101, P0102, P0103, P0117, P0118, P0116, P0128, P0500, P0608, or P0609 are not set. |
| • | The electronic coolant temperature (ECT) sensor is greater than -40°C (-40°F). |
| • | The mass air flow (MAF) sensor is less than 512 g/s. |
| • | The engine run time is more than 10 seconds. |
| • | DTC P0112 runs continuously within the above enable conditions. |
Conditions for Setting the DTC
P0112
The IAT sensor is more than 148°C (298°F) for more than 5 seconds.
P0113
The IAT sensor is less than -39°C (-38°F) for more than 5 seconds.
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, 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.
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
Important:
• Perform this verification procedure only when the ignition has been OFF for 8 hours or more. • The IAT will begin to warm up as soon as the ignition key is turned ON
- Ignition ON, observe the scan tool IAT Sensor, IAT Sensor 2, and ECT Sensor parameters. The readings should be within 15°C (27°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 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 ground. Verify the scan tool IAT Sensor parameter is greater than 149°C (300°F).
- If all circuits test normal, test the MAF/IAT sensor. Refer to Component Testing for instructions.
| ⇒ | 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 E 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
Compare the IAT sensor resistance to the values listed in the Temperature vs. Resistance table. Refer to Temperature Versus Resistance .
| ⇒ | If the resistance is not within the range listed in the Temperature vs. Resistance table, replace the IAT sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
