P0137

DTC P0131, P0132, P0134, P0137, P0138, or P0140

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 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

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 0-1 275 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

DTC P0131 or P0137

* DTCs P0068, P0106, P0108, P0122, P0123, P0201, P0202, P0203, P0204, P0222, P0223, P0442, P0443, P0449, P0452, P0455, P0496, P0606, P16F3 and P2101 are not set.

* The system voltage is between 10-32 V.

* The fuel level is greater than 10%.

* The fuel composition is less than 87% ethanol.

* The fuel system is in Closed Loop.

* The engine is not decelerating.

* DTC P0131 runs continuously when the above conditions are met for greater than 3 s.

* DTC P0137 runs continuously when the above conditions are met for greater than 5 s.

DTC P0132 or P0138

* DTCs P0106, P0108, P0201, P0202, P0203, P0204, P0442, P0443, P0449, P0452, P0453, P0455 and P0496 are not set.

* The system voltage is between 10-32 V.

* The fuel level is greater than 10%.

* The fuel composition is less than 87% ethanol.

* The fuel system is in Closed Loop.

* The engine runtime is greater than 5 s.

* The engine is not decelerating.

* DTC P0132 and P0138 run continuously when the above conditions are met for greater than 3 s.

DTC P0134 or P0140

* DTCs P0068, P0101, P0102, P0103, P0122, P0123, P0222, P0223, P0606 and P16F3 are not set.

* The ignition voltage is between 10-32 V.

* HO2S heater warm up is finished.

* The engine runtime is greater than 5 s.

* The fuel composition is less than 87% ethanol.

* DTC P0134 and P0140 run continuously when the above conditions are met.

Conditions for Setting the DTC

P0131 or P0137

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

P0132 or P0138

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

P0134 or P0140

The ECM detects that the heated oxygen sensor (HO2S) voltage is greater than 1 700 mV for greater than 10 s.

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC

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

Reference Information

Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

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

1. Ignition ON, observe the DTC information with a scan tool. Verify no HO2S heater DTCs are set.

• If a HO2S heater DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

2. Engine running, observe the scan tool HO2S 1 or HO2S 2 voltage parameters. The reading should be within the range of 20-1 050 mV.

3. Operate the vehicle within the Conditions for Running the DTC to verify 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 appropriate B52 Heated Oxygen Sensor.

2. Ignition OFF, all vehicles systems OFF. It may take up to 2 min for all vehicle systems to power down. Test for less than 5 ohms between the low signal circuit terminal 3 and ground.

• If greater than the specified range, test the low signal circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

3. Ignition ON, test for 1.5-3.0 V between the high signal circuit terminal 4 and ground.

• If less than the specified range, test the high signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

• If greater than the specified range, test the high signal circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

4. Verify none of the following conditions exist:

* Lean or rich fuel injectors - Refer to Fuel Injector Diagnosis Fuel Injector Diagnosis.

* Water intrusion in the HO2S harness connector

* Low or high fuel system pressure - Refer to Fuel System Description Fuel System Description.

* Fuel that is contaminated - Refer to Alcohol/Contaminants-in-Fuel Diagnosis Testing and Inspection.

* Fuel saturation of the evaporative emission (EVAP) canister

* Exhaust leaks near the HO2S

* Engine vacuum leaks

• If you find any of the above conditions, repair as necessary.

5. If all circuits test normal, replace the B52 Heated Oxygen Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic repair.

* Heated Oxygen Sensor Replacement - Sensor 1 Heated Oxygen Sensor Replacement - Sensor 1

* Heated Oxygen Sensor Replacement - Sensor 2 Heated Oxygen Sensor Replacement - Sensor 2

* Perform the scan tool Heated Oxygen Sensor Resistance Learn Reset after replacing a HO2S.

* Control Module References Control Module References for ECM replacement, programming, and setup.