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 Descriptor
DTC P0111: Intake Air Temperature (IAT) Sensor PerformanceDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
IAT Sensor Signal | P0110, P0112 | P0110, P0113 | P0110, P0113 | P0111, P011B |
Low Reference | -- | P0110, P0113 | -- | P0111, P011B |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: -40 to +140°C (-40 to +284°F) Varies with coolant temperature. | |||
IAT Sensor Signal | 140°C (284°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F) |
Circuit Description
The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the engine coolant. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit. The PCM monitors the mutual performance of the IAT and the engine coolant temperature (ECT) signals. The PCM monitors the warm up and cool down behavior of the sensors, after a vehicle driven at operating temperature is shut down. If the PCM detects that the IAT is not with in a predetermined range of ECT after a long soak, or the IAT and ECT are not within a range of each other, as compared to a previous cold start, this DTC sets.
The following table illustrates the difference between temperature, resistance, and voltage:
Temperature | ECT Resistance | ECT Signal Voltage |
|---|---|---|
Cold | High | High |
Warm | Low | Low |
Conditions for Running the DTC
| • | The engine coolant temperature is at a specified value at engine start up. |
| • | The engine has been running for greater than 250 seconds. |
| • | Vehicle speed has exceeded 65 km/h (40 mph). |
| • | DTC P0111 runs once per ignition cycle when the above conditions are met. |
Conditions for Setting the DTC
The IAT sensor input changes less than a specified value during engine warm up.
Action Taken When the DTC Sets
DTC P0111 is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P0111 is a Type B DTC.
Diagnostic Aids
| • | Test the IAT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a DTC or a driveability condition. Refer to Temperature Versus Resistance. |
| • | If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F). |
| • | High resistance in the circuit of the ECT sensor could set a DTC. |
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 idling for 1 minute, observe the DTC information with a scan tool. DTCs P0110, P0112 and 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.
| ⇒ | If any of the DTCs are set, refer to DTC P0110, P0112, or P0113. |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
- Test for less than 10 ohms between the low reference circuit terminal 2 and ground G104.
- Ignition ON, verify that the IAT sensor parameter is at -40°C (-40°F).
- Install a 3A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the IAT sensor parameter is greater than 139°C (280°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 or a short to voltage. If the circuit tests normal, replace the PCM. |
| ⇒ | If greater than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the PCM. |
| ⇒ | 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 PCM. |
Component Testing
- Ignition OFF, disconnect the harness connector at the MAF/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 control module replacement, setup, and programming |
