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 | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
IAT Sensor Signal | P0112 | P0111, P0113 | P0113 | P0113 | P0111 |
Low Reference | -- | -- | -- | -- | -- |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
IAT Sensor Signal | -39°C to +120°C (-38°F to +248°F) | 149°C (300°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -- | -- | -- |
Circuit/System Description
The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor 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
Important: Before the ECM can report DTC P0111 failed, DTC P0116 must run.
| • | DTCs P0112, P0113, P0117, P0118, P0128, P0502, P0503, P0601, P1621, P1627, P1680, P1681, P2610 are not set. |
| • | The vehicle has had a minimum ignition OFF time of 8 hours. |
| • | The ignition is ON. |
| • | The start-up IAT is greater than 10°C (50°F). |
| • | The Fuel Level Sensor parameter is greater than 2.5 percent. |
| • | This DTC runs once per ignition cycle within the enabling conditions. |
Conditions for Setting the DTC
Important: Before the ECM can report DTC P0111 failed, DTC P0116 must run.
| • | The ECM detects a temperature difference at power-up that indicates that the IAT sensor is 30°C (54°F) more than the IAT sensor 2. |
| OR |
| • | The ECM detects a temperature difference at power-up that indicates that the IAT sensor is 16°C (29°F) more than the IAT sensor 2, and the time spent cranking the engine is more than 30 seconds, when the fuel level is more than 2.5 percent. |
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
- An IAT sensor that is skewed lower at various ambient temperatures, due to more resistance than is normal, can widen the spread between the 4 sensors and cause this DTC to set. Measure and record the resistance of the IAT sensor at various ambient temperatures, and then compare those measurements to the Temperature vs. Resistance Table. Refer to Temperature Versus Resistance .
- Inspect the mass air flow (MAF)/IAT sensor terminals for corrosion.
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
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, IAT Sensor 2, and ECT Sensor parameters. The readings should be within 15°C (27°F) of each other and also the ambient temperature.
- Engine running, observe the DTC information with a scan tool. DTC P0111 should 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 data.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
- Test for less than 5 ohms of resistance between the low reference circuit of the IAT terminal D and ground.
- Disconnect the harness connector at the IAT sensor 2.
- Test for less than 5 ohms of resistance between the low reference circuit of the IAT sensor 2 terminal B and ground.
- Disconnect the harness connector at the ECM.
- Test for less than 5 ohms of resistance between the IAT signal circuit terminal E and the corresponding terminal at the ECM.
- Test for less than 5 ohms of resistance between the IAT sensor 2 signal circuit terminal A and the corresponding terminal at the ECM.
- If all circuits test normal, test the IAT sensor and the IAT sensor 2. Refer to Component Testing.
| ⇒ | If greater than the specified range, test the low reference circuit for high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the low reference circuit for high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, repair the high resistance on the signal circuit. |
| ⇒ | If greater than the specified range, repair the high resistance on the signal circuit. |
Component Testing
Measure and record the resistance of the IAT sensor and IAT sensor 2 at various ambient temperatures, and then compare those measurements to the Temperature vs. Resistance Table. Refer to Temperature Versus Resistance .
| ⇒ | If the resistance of either sensor is not within 10 percent of the range listed in the Temperature vs Resistance table, replace the affected sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
