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 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 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
P0112
| • | DTC P0113 is not set. |
| • | Battery voltage is more than 7 V. |
| • | Key switch is ON. |
P0113
| • | DTC P0112 is not set. |
| • | Battery voltage is between 10-16 V. |
| • | Key switch is ON. |
| • | Engine is running for more than 10 seconds. |
Conditions for Setting the DTC
P0112
IAT sensor voltage is less than 0.1 V.
P0113
IAT sensor voltage is more than 4.9 V.
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
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
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.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the mass air flow (MAF)/IAT sensor.
- Ignition OFF, test for less than 5 ohms 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 |
