Chevrolet Trax: DTC P00F4-P00F6

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 Descriptors

DTC P00F4

Intake Air Humidity Sensor Circuit Low Voltage

DTC P00F5

Intake Air Humidity Sensor Circuit High Voltage

DTC P00F6

Intake Air Humidity Sensor Circuit Erratic

Diagnostic Fault Information

Intake Air Humidity Sensor

Typical Scan Tool Data

Intake Air Humidity

Circuit/System Description

The sensors listed below are integrated within the multifunction intake air sensor:

• IAT sensor 1
• IAT sensor 2
• Humidity sensor
• MAF sensor
• BARO pressure sensor

The intake air humidity sensor measures the ambient humidity of the air in the sensor bore. The signal varies with intake air humidity and is displayed by the scan tool as duty cycle %. The engine control module (ECM) applies 5 V to the signal circuit. The humidity sensor and the IAT sensor 2 share the same circuit.

The sensors listed below share an ECM supplied 5 V reference circuit:

• IAT sensor 2
• Humidity sensor
• Barometric pressure (BARO) sensor

The sensors listed below share an ECM supplied low reference circuit:

• IAT sensor 1
• IAT sensor 2
• Humidity sensor
• Barometric pressure (BARO) sensor

Conditions for Running the DTCs

P00F4, P00F5, and P00F6

• DTC P1682 is not set.
• The ignition is ON.
• The Ignition voltage is at least 11 V.
• These DTCs run continuously within the enabling conditions.

Conditions for Setting the DTCs

P00F4

The ECM detects that the humidity sensor signal is less than or equal to 5 % for greater than 5 s.

P00F5

The ECM detects that the humidity sensor signal is greater than or equal to 95 % for greater than 5 s.

P00F6

The ECM detects that the humidity sensor signal is intermittent or has abruptly changed over a period of time greater than s.

Action Taken When the DTC Sets

DTCs P00F4,P00F5, and P00F6 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P00F4,P00F5, and P00F6 are Type B DTCs.

Diagnostic Aids

• The Intake Air Humidity Signal parameter displays the measured humidity within the air intake system and may differ from atmospheric humidity measured outside the air intake system.
• The humidity sensor and the IAT sensor 2 signals are sent to the ECM on the same circuit. If the Intake Air Humidity parameter displays the value: 0 % or 100 %, and there are also IAT Sensor 2 DTCs, check for a circuit problem.

Reference Information

Schematic Reference

Engine Controls Schematics (Encore) , Engine Controls Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Powertrain Component Views

Powertrain Component Views

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (LUV) , Powertrain Diagnostic Trouble Code (DTC) Type Definitions (2H0)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-38522-A Variable Signal Generator

For equivalent regional tools, refer to Special Tools (Diagnostic Tools) .

Circuit/System Verification

1. Ignition ON, verify that DTC DTC P0641, P0651, P0697, or P06A3 is not set.

If any of the DTCs are set

Refer to DTC P0641, P0651, P0697, or P06A3 (ECM) for further diagnosis.

If none of the DTCs are set

NOTE: To minimize the effects of residual engine heat and sensor internal heating elements, perform Steps 2 and 3 of this verification procedure only if the ignition has been OFF for 8 hours or more.

2. Ignition ON.
3. Verify the following scan tool parameters are within 25ºC (45ºF) of each other.

• Start-Up IAT Sensor 1
• IAT Sensor 2
• IAT Sensor 3; where equipped

If not within 25ºC (45ºF)

Refer to Circuit/System Testing.

If within 25ºC (45ºF)

4. Engine idling, verify the scan tool Intake Air Humidity parameter is between 5 and 90 %.

If not between 5 and 90 %

Refer to Circuit/System Testing.

If between 5 and 90 %

5. 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.
6. Verify the DTC does not set.

If the DTC sets

Refer to Circuit/System Testing.

If the DTC does not set

7. All OK

Circuit/System Testing

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, and all vehicle systems OFF, it may take up to 2 min. for all vehicle systems to power down. Disconnect the harness connector at the B75C Mass Air Flow/Multifunction Intake Air sensor.
2. Test for less than 2 ohms between the low reference circuit terminal 7 and ground.

If 2 ohms or greater

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 ohms in the low reference circuit end to end.

• If 2 ohms or greater, repair the open or high resistance in the circuit.
• If less than 2 ohms replace the K20 Engine Control Module.

If less than 2 ohm

3. Ignition OFF, all vehicle systems OFF, test for less than 2 ohms between the ground circuit terminal 4 and ground.

If 2 ohms or greater

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open or high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.

If less than 2 ohms

4. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 2 and ground.

If less than 4.8 V

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.

If greater than 5.2 V

NOTE: If the 5 V reference circuit is shorted to a voltage the engine control module or the sensor may be damaged.

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Ignition ON, test for less than 1 V between the 5 V reference circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 Engine Control Module.

If between 4.8-5.2 V

5. Ignition ON, test for 4.8-5.2 V between the humidity signal circuit terminal 1 and ground.

If less than 4.8 V

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.

If greater than 5.2 V

NOTE: If the signal circuit is shorted to a voltage the engine control module or the sensor may be damaged.

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Ignition ON, test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 Engine Control Module.

If between 4.8-5.2 V

6. Determine if EL-38522-A Variable Signal Generator or equivalent is available.

EL-38522-A, Variable Signal Generator; or equivalent is not available

1. Replace the K20 Engine Control Module.
2. 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.
3. Verify the DTC does not set.

If the DTC sets

Refer to step 10.

If the DTC does not set

4. All OK.

EL-38522-A, Variable Signal Generator; or equivalent is available

7. Ignition OFF, connect the leads of the EL-38522-A Variable Signal Generator as follows:

• Red lead to the signal circuit terminal 1 at the harness connector
• Black leads to ground
• Battery voltage supply lead to B+

8. Set the EL-38522-A Variable Signal Generator to the following specifications.

• Signal switch to 5 V
• Frequency switch to 250 Hz
• Duty Cycle switch to 50 % (Normal)

9. Ignition ON, verify the scan tool Intake Air Humidity parameter is between 45-55 %.

If not between 45-55 %

Replace the K20 Engine Control Module.

If between 45-55 %

10. Test or replace the B75C Multifunction Intake Air sensor.

Component Testing

Multifunction Intake Air Sensor

1. Test the Intake Air Humidity Sensor by varying the air humidity in the intake duct near the sensor, while observing the scan tool Intake Air Humidity Sensor parameter. The parameter should change and be within 5-95%.

If not within 5-95%.

Replace the B75C Multifunction Intake Air sensor.

If within 5-95%.

2. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Mass Airflow Sensor Replacement for multifunction intake air sensor replacement.
• Control Module References for Engine Control Module replacement, programming, and setup.

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