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 P1111: Intake Air Temperature (IAT) Sensor Circuit Intermittent High VoltageDTC P1112: Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
IAT Sensor Signal | P0112, P1112 | P0113, P1111 | P0113, P1111¹ | P0110, P0111 |
Low Reference | -- | P0113, P1111 | P0113, P1111¹ | P0110, P0111 |
¹ Internal ECM or sensor damage may occur if the circuit is shorted to B+. | ||||
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 | 130°C (266°F) | 20°C (68°F) | 20°C (68°F)¹ |
Low Reference | -- | 20°C (68°F) | -- |
¹ Internal ECM or sensor damage may occur if the circuit is shorted to B+. | |||
Circuit/System 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
P1111
| • | DTCs P0117, P0118, and P0502 are not set. |
| • | The engine run time is greater than 120 seconds. |
| • | The engine airflow is less than 15 g/s. |
| • | The engine coolant temperature (ECT) sensor is greater than 70°C (158°F). |
| • | The vehicle speed is less than 25 km/h (15 mph). |
| • | This DTC runs continuously once the above conditions are met. |
P1112
| • | DTC P0502 is not set. |
| • | The engine run time is greater than 120 seconds. |
| • | The vehicle speed is greater than 50 km/h (31 mph). |
| • | This DTC runs continuously once the above conditions are met. |
Conditions for Setting the DTC
P1111
The ECM detects that the IAT sensor parameter is less than -38°C (-36°F) for greater than 3 seconds intermittently.
P1112
The ECM detects that the IAT sensor is greater than 149°C (300°F) for greater than 20 seconds intermittently.
Action Taken When the DTC Sets
DTCs P1111 and P1112 are Type C DTCs.
Conditions for Clearing the MIL/DTC
DTCs P1111 and P1112 are Type C DTCs.
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
- Verify that DTCs P0112 or P0113 are 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. DTC P1111 or P1112 should not set.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
- Start the engine. Observe the intake air temperature (IAT) sensor parameter while moving the harness connector of the sensor. The IAT sensor parameter should not change abruptly.
- Engine running, observe the IAT sensor parameter while moving the harness connector of the ECM. The IAT sensor parameter should not change abruptly.
- Engine running, observe the IAT sensor parameter while moving the wiring harness between the sensor and ECM. The IAT sensor parameter should not change abruptly.
| ⇒ | If the IAT sensor parameter changes abruptly, repair the harness connector of the IAT sensor. |
| ⇒ | If the IAT sensor parameter changes abruptly, repair the harness connector of the ECM. |
| ⇒ | If the IAT sensor parameter changes abruptly, repair the wiring harness. |
Component Testing
- Ignition OFF, disconnect the harness connector of 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 the resistance vs. temperature is not within 5 percent, replace the IAT sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
