P0111
DTC P0111 (Heavy Duty L96 and LC8)
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 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:
Conditions for Running the DTC
* DTCs P0112, P0113, P0117, P0118 are not set.
* The ignition has been OFF at least 8 hours.
* The ignition is ON.
* This DTC runs once per ignition cycle when the enabling conditions are met.
Conditions for Setting the DTC
The ECM determines the absolute difference between IAT start-up temperature and the ECT start-up temperature is greater than 20°C (36°F).
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
* The use of non-thermostatically controlled aftermarket block heater will cause this DTC to set.
* An IAT sensor that is skewed, due to more resistance than is normal, can widen the spread between the 2 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.
* A slight to moderate resistance in the IAT sensor signal circuit or low reference circuit will increase the range between these two sensors. This condition results in a greater voltage on the IAT sensor signal circuit, which is interpreted by the ECM as a colder IAT.
* Inspect the mass air flow MAF/IAT sensor terminals for corrosion.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
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 Control Module References 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. Inspect the thermostatically-controlled coolant heater, if equipped, for damage or modifications. Test for proper operation of the coolant heater. Refer to Coolant Heater Inoperative (without Diesel) Coolant Heater Inoperative (Without Diesel)Coolant Heater Inoperative (with Diesel) Coolant Heater Inoperative (With Diesel).
2. Ignition ON, observe the scan tool IAT Sensor and ECT Sensor parameters. The readings should be within 20°C (36°F) of each other and ambient temperature.
3. 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 harness connector at the B75B MAF/IAT sensor.
2. Ignition OFF, all vehicles systems OFF. It may take up to for 2 minutes for all vehicle systems to power down. Test for less than 5 ohms 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 K20 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 K20 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 K20 ECM.
5. If all circuits test normal, test or replace the B75B MAF/IAT sensor.
Component Testing
1. Ignition OFF, disconnect the harness connector at the IAT sensor.
Note:
A thermometer can be used to test the sensor off the vehicle.
2. Test the IAT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance Temperature Versus Resistance
• If not within the specified range, replace the IAT sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Mass Airflow Sensor with Intake Air Temperature Sensor Replacement Service and Repair
* Control Module References Control Module References for ECM replacement, setup, and programming