Chevrolet Trax: DTC P0131, P0132, P0134, P0137, P0138, OR P0140 (LUJ)

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 provide an overview of each diagnostic category.

DTC Descriptors

DTC P0131

HO2S Circuit Low Voltage Sensor 1

DTC P0132

HO2S Circuit High Voltage Sensor 1

DTC P0134

HO2S Circuit Insufficient Activity Sensor 1

DTC P0137

HO2S Circuit Low Voltage Sensor 2

DTC P0138

HO2S Circuit High Voltage Sensor 2

DTC P0140

HO2S Circuit Insufficient Activity Sensor 2

Diagnostic Fault Information

Typical Scan Tool Data

HO2S 1 or 2

Circuit/System Description

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an open loop mode, ignoring the HO2S signal voltage while calculating the air to fuel ratio. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1 000 mV. Once sufficient HO2S voltage fluctuation is observed by the control module, closed loop is entered. The control module uses the HO2S voltage to determine the air to fuel ratio. An HO2S voltage that increases toward 1 000 mV indicates a rich fuel mixture. An HO2S voltage that decreases toward 0 mV indicates a lean fuel mixture.

The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster.

This allows the system to enter closed loop earlier and the control module to calculate the air to fuel ratio sooner.

Conditions for Running the DTC

P0131, P0132, P0137, or P0138

• DTC P0030, P0036, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0443, or P2135 is not set.
• The engine is operating.
• The ignition voltage is between 10-32 V.
• The fuel system is in closed loop.
• The vehicle is not decelerating.
• The DTC runs continuously when the above conditions are met for 5 s.

P0134

• The ECM detects that the heated oxygen sensor (HO2S) 1 parameter is between 400-500 mV for 100 s.
• The throttle position indicated angle parameter changes more than 1%, 3 times.
• DTC P0134 sets within 100 s when the above condition is met.

P0140

• The ECM detects that the heated oxygen sensor (HO2S) 2 parameter is between 425-475 mV.
• The throttle position indicated angle parameter changes more than 1%, 3 times.
• DTC P0140 sets within 100 s when the above conditions are met.

Conditions for Setting the DTC

P0131

The engine control module (ECM) detects that the heated Oxygen Sensor (HO2S) voltage is less than 20 mV for greater than 38 s.

P0132 and P0138

The ECM detects that the heated Oxygen Sensor (HO2S) voltage is greater than 1 050 mV for greater than 10 s.

P0134

• The ECM detects that the heated oxygen sensor (HO2S) 1 parameter is between 400-500 mV for 100 s.
• The throttle position indicated angle parameter changes more than 1%, 3 times.
• DTC P0134 sets within 100 s when the above conditions are met.

P0137

The engine control module (ECM) detects that the heated Oxygen Sensor (HO2S) voltage is less than 20 mV for greater than 43 s.

P0140

• The ECM detects that the heated oxygen sensor (HO2S) 2 parameter is between 425-475 mV.
• The throttle position indicated angle parameter changes more than 1%, 3 times.
• DTC P0140 sets within 100 s when the above conditions are met.

Action Taken When the DTC Sets

DTC P0131, P0132, P0134, P0137, P0138, and P0140 are Type B DTCs

Conditions for Clearing the DTC

DTC P0131, P0132, P0134, P0137, P0138, and P0140 are Type B DTCs.

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

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

Circuit/System Verification

1. Ignition ON.
2. Verify no HO2S heater DTCs are set.

• If a DTC is set.

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

• If a DTC is not set.

3. Engine running.
4. Verify the scan tool HO2S Sensor 1 or 2 parameters are between 50-1,050 mV.

• If not between 50-1,050 mV.

Refer to Circuit/System Testing.

• If between 50-1,050 mV.

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

1. Ignition OFF and all vehicle systems OFF, disconnect the appropriate B52 Heated Oxygen Sensor harness connector. It may take up to 2 minutes for all vehicle systems to power down. Ignition ON.
2. Test for 1.7-3.0 V between the high signal circuit terminal 4 and ground.

• If less than 1.7 V.

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for the infinite resistance between the high signal circuit terminal 4 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 high 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 3 V

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the high signal circuit terminal 4 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 1.7-3.0 V

3. Verify the scan tool heated oxygen sensor 1 or 2 parameter is between 1.7-3.0 V.

• If less than 1.7 V

1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for infinite resistance between the low signal circuit terminal 3 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K20 Engine Control Module.
• If greater than 1.7 V

4. Connect a 3 A fused jumper wire between the high signal circuit terminal 4 and the low signal circuit terminal 3.

NOTE: The low signal circuit is tied to a pull-up circuit within the engine control module. A voltage of 0.0-1.1 V on the low signal circuit is normal.

5. Verify the scan tool heated oxygen sensor 1 or 2 voltage parameter displays 0.0 V.

• If greater than 0.0 V

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

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

3. Test for less than 1 V between the low signal circuit terminal 3 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 0.0 V

6. Verify none of the conditions listed below exist:

• Water intrusion in the B52 Heated Oxygen Sensor harness connector
• Low or high fuel system pressure-Refer to Fuel System Diagnosis (LUJ) , Fuel System Diagnosis (LUV) .
• Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
• Fuel saturation of the evaporative emission (EVAP) canister
• Exhaust leaks
• Engine vacuum leaks
• If any of the conditions exist

Repair as necessary.

• If none of the conditions exist

7. Test or replace the B52 Heated Oxygen Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• Heated Oxygen Sensor Replacement - Sensor 1
• Heated Oxygen Sensor Replacement - Sensor 2
• Perform the scan tool Heated Oxygen Sensor Resistance learn Reset after replacing a heated oxygen sensor.
• Control Module References for ECM replacement, programming and setup

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