P0111
DTC P0111
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0111
- Intake Air Temperature (IAT) Sensor Performance
Diagnostic Fault Information
Typical Scan Tool Data
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 5V 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
Note: 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 warmer than 10°C (50°F).
* The Fuel Level Sensor parameter is greater than 2.5 percent.
* This DTC runs once per ignition cycle when the enabling conditions are met.
Conditions for Setting the DTC
Note: 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 20°C (36°F) greater 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) greater than the IAT sensor 2, and the time spent cranking the engine is greater than 30 seconds, when the fuel level is greater 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
1. 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 (Temperature Versus Resistance).
2. Inspect the mass air flow (MAF)/IAT sensor terminals for corrosion.
Reference Information
Schematic Reference
Engine Controls Schematics (LS3) ([1][2]Electrical Diagrams)Engine Controls Schematics (LS7) ([1][2]Electrical Diagrams)Engine Controls Schematics (LS9) ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Note: Perform this verification procedure only if the ignition has been OFF for 8 hours or more.
1. 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.
2. Operate the vehicle within the Conditions for Running the DTC to verify that 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
1. Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
2. Ignition OFF, all vehicles systems OFF, this may take up to for 2 min, test for less than 5 ohm of resistance between the low reference circuit terminal D and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, verify the scan tool IAT Sensor parameter is colder than -39°C (-38°F).
• If warmer than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
4. Install a 3 A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool IAT Sensor parameter is warmer than 149°C (300°F).
• If colder 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.
5. If all circuits test normal, test or replace the MAF/IAT sensor.
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 (Temperature Versus Resistance).
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Intake Air Temperature Sensor Replacement (LS9) (Intake Air Temperature Sensor Replacement)
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (Mass Airflow Sensor With Intake Air Temperature Sensor Replacement)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming