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 | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
IAT Sensor Signal | P0112 | P0113 | P0113 | -- |
Low Reference | -- | P0113 | P0113 | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop Parameter Normal Range: Varies with ambient temperature | |||
IAT Sensor Signal | 141°C (286°F) | -40°C (-40°F) | -40°C (-40°F)* |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)* |
* Internal ECM or sensor damage may occur if the circuit is shorted to B+. | |||
Circuit Description
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air entering the engine. The IAT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit.
The following table illustrates the difference between temperature, resistance, and voltage:
IAT | IAT Resistance | IAT Signal Voltage |
|---|---|---|
Cold | High | High |
Warm | Low | Low |
Conditions for Running the DTC
P0112
| • | DTC P0502 is not set. |
| • | The engine run time is more than 120 seconds. |
| • | The vehicle speed is greater than 30 km/h (19 mph). |
| • | The DTC runs continuously once the above conditions are met. |
P0113
| • | DTCs P0106, P0107, P0108, P0117, P0118, and P0502 are not set. |
| • | The calculated engine airflow is less than 15 g/s. |
| • | The vehicle speed is less than 25 km/h (15 mph). |
| • | The engine coolant temperature (ECT) is greater than 50°C (122°F). |
| • | The engine run time is more than 120 seconds, or the ignition has been off for more than 8 hours before vehicle is started. |
| • | The DTC runs continuously once the above conditions are met. |
Conditions for Setting the DTC
P0112
The ECM detects that the IAT sensor is greater than 138°C (280°F) for greater than 10 seconds.
P0113
The ECM detects that the IAT sensor parameter is less than -45°C (-49°F) for greater than 4 seconds.
Action Taken When the DTC Sets
| • | DTC P0112 and P0113 are Type B DTCs. |
| • | The cooling fans will be commanded ON by the ECM. |
Conditions for Clearing the MIL/DTC
DTC P0112 and P0113 are Type B DTCs.
Diagnostic Aids
If the vehicle has set overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F).
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
- Engine running for 4 minutes, 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 to verify 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
- Ignition OFF, disconnect the harness connector at the IAT sensor.
- Ignition ON, clear the DTC information with a scan tool.
- Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal 2 and ground.
- Ignition ON, verify the scan tool IAT sensor parameter is at -40°C (-40°F).
- Ignition ON, clear the DTC information with a scan tool.
- Install a 1A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool IAT sensor parameter is greater than 135°C (275°F).
- If all circuits test normal, test or replace 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 for a short to ground. If the circuit tests normal, replace the ECM. |
Important: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.
| ⇒ | 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
- Ignition OFF, disconnect the harness connector at the IAT sensor.
- Test the IAT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance table and verify that the resistance is within 5 percent of the specification.
Important: A thermometer can be used to test the sensor off the vehicle.
| ⇒ | If not within the specified range, 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. |
