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DTC P0111 (LF1)

DTC P0111 (LF1)

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 Performance

Diagnostic Fault Information

IAT Sensor

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
IAT Sensor Signal P0112, P0114 P0111, P0113, P0114 P0113*, P0114 P0111
Low Reference - P0111, P0113, P0114 P0113*, P0114 P0111
*Internal ECM or sensor damage may occur if the circuit is shorted to B+.


Typical Scan Tool Data

IAT Sensor

Circuit Short to Ground Open or High Resistance Short to Voltage
Operating Conditions: Engine Running Parameter Normal Range: Varies with ambient temperature
IAT Sensor Signal 150°C (302°F) -40°C (-40°F) -40°C (-40°F)*
Low Reference - -40°C (-40°F) -40°C (-40°F)*
*Internal ECM or sensor damage may occur if the circuit is shorted to B+


Typical Scan Tool Data

ECT Sensor

Circuit Short to Ground Open or High Resistance Short to Voltage
Operating Conditions: Engine Running Parameter Normal Range: Varies with coolant temperature
ECT Sensor Signal 150°C (302°F) -40°C (-40°F) -40°C (-40°F)*
Low Reference - -40°C (-40°F) -40°C (-40°F)*
*Internal ECM or sensor damage may occur if the circuit is shorted to B+


Circuit/System Description

The intake air temperature (IAT) sensor is integrated with the mass air flow (MAF) sensor. It 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.

IAT IAT Resistance IAT Signal Voltage
Cold High High
Warm Low Low


Conditions for Running the DTC


• DTCs P0112, P0113, P0117, P0118 are not set.

• The vehicle 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 DTC

DTC P0111 is a Type B DTC.

Diagnostic Aids


• 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 - Intake Air Temperature Sensor .

• 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/intake air temperature sensor terminals for corrosion.


Reference Information

Schematic Reference

Engine Controls Schematics (3.0L (LF1)) Engine Controls Schematics (2.8L (LAU))

Connector End View Reference

Component Connector End Views

Electrical Information Reference


• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs


DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Note

Perform Step 1 of this verification procedure only if the ignition has been OFF for 8 hours or more.



1. Ignition ON, observe the following scan tool parameters. The readings should be within 20°C (36°F) of each other.

• Start-Up IAT

• Start-Up ECT

2. Engine running, observe the scan tool IAT sensor parameter. The reading should be between -38 and +149 °C (-36 and +300 °F), depending on the current ambient temperature and the vehicle operating conditions.

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 mass air flow/intake air temperature sensor.

2. Remove the fuse that supplies B+ to terminal 52 X1 of the ECM.

3. Ignition OFF, all systems OFF. It may take up to for 2 minutes for all vehicle systems to power down. Test for less than 5 Ω between the low reference circuit terminal D and ground.

4. 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.

5. Ignition ON, verify the scan tool IAT Sensor parameter is colder than -39°C (-38°F).

6. If warmer than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

7.
Note

If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the ECM or the sensor may be damaged.


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).

8. 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.

9. If all circuits test normal, test or replace the B75B mass air flow/intake air temperature sensor.


Component Testing


1. Ignition OFF, disconnect the harness connector at the B75B mass air flow/intake air temperature sensor.

2.
Note

A thermometer can be used to test the sensor off the vehicle.


Test the IAT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance - Intake Air Temperature Sensor . The resistance values should be in range of the table values.

3. If not within the specified range, B75B mass air flow/intake air temperature sensor.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (LAU) Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (LF1)

• Control Module References for ECM replacement, setup, and programming