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 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, P1111* | P0110, P0111 |
Low Reference | -- | P0113, P1111 | P0113, P1111* | P0110, P0111 |
* 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 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 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
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, observe the DTC information with a scan tool. Verify that DTC P0112, or P0113 is not set.
- Observe the DTC information with a scan tool. DTCs P1111 or P1112 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.
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
Engine running, observe the scan tool intake air temperature (IAT) sensor parameter while moving the related wiring harness and harness connectors. The reading should not change abruptly.
| ⇒ | If the reading changes abruptly, repair the wiring harness and harness connectors. |
Component Testing
- Ignition OFF, disconnect the harness connector at the intake air temperature (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 engine control module replacement, setup, and programming |
