P0134
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 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
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 engine control module (ECM) 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 0-1,900 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.
This ECM uses a high bias voltage on the high and low signal circuits of the HO2S. The voltage measured between the low signal terminal and ground varies based on the temperature of the sensor and will typically be between 0-1,000 mV under normal operating conditions. The value of the high signal terminal measured to ground is equal to the value of the low signal measured to ground plus the 1,900 mV bias between the low signal and the high signal. In closed loop, the sensor functions in the same voltage range as systems with the low bias voltage. In open loop or open circuit conditions, the high bias voltage is present and takes the voltage outside of the normal operating range for easier fault detection.
Conditions for Running the DTC
P0131 or P0137
* DTCs P0106, P0107, P0108, P0122, P0123, P0201, P0202, P0203, P0204, P0222, P0223, P0442, P0443, P0449, P0452, P0453, P0455, P16F3, P2101, or P2135 are not set.
* The engine is running.
* The ignition voltage is between 10-32 V.
* The fuel system is in Closed Loop.
* The fuel control system is not in decel fuel cut off.
* The ECM is not performing any intrusive diagnostic tests.
* A scan tool output device control is not active.
* The fuel level is greater than 10 percent.
* Fuel has less than or equal to 87 percent ethanol.
* The DTCs run continuously when the above conditions are met for 5 s.
P0132 or P0138
* DTCs P0106, P0107, P0108, P0122, P0123, P0201, P0202, P0203, P0204 , P0222, P0223, P0411, P0442, P0443, P0449, P0452, P0453, P0455, P16F3, P2101, P2135, P2440, P2444 are not set.
* The ignition voltage is between 10-32 V.
* Fuel has less than or equal to 87 percent ethanol.
* The engine is running for greater than 195 s.
* The fuel level is greater than 10 percent.
* The fuel control is not in power enrichment.
* The DTCs run continuously when the above conditions are met for 5 s.
P0134 or P0140
* DTCs P0101, P0102, P0103, P0122, P0123, P0222, P0223, P16F3, P2101, P2103, P2135 are not set.
* The HO2S heaters are at operating temperature.
* The ignition voltage is between 10-32 V.
* The engine run time is greater than 150 s.
* DTC P0134 runs continuously when the above conditions are met.
Conditions for Setting the DTC
P0131 or P0137
The ECM detects that the HO2S voltage is less than 50 mV for greater than 48 s for DTC P0131 or 54 s for DTC P0137.
P0132 or P0138
The ECM detects that the HO2S voltage is greater than 1,050 mV for greater than 13 s.
P0134 or P0140
The ECM detects that the HO2S voltage is greater than 1,700 mV for greater than 25 s.
Action Taken When the DTC Sets
DTCs P0131, P0132, P0137, and P0138 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0131, P0132, P0137, and P0138 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1
Description and Operation
Hybrid Modes of Operation Description Hybrid Modes of Operation Description
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 Programming and Relearning for scan tool information
Circuit/System Verification
1. Vehicle in Service Mode, observe the DTC information with a scan tool. Verify no HO2S heater DTCs are set.
• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Engine running, observe the appropriate scan tool HO2S 1 or 2 voltage parameter. The reading should vary between 50-1,050 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. Vehicle OFF, disconnect the harness connector at the appropriate B52 HO2S.
2. Vehicle in Service Mode, observe the scan tool HO2S 1 or 2 voltage parameter. The parameter should display between 1,850-1,950 mV.
• If less than the specified range, test the high and low signal circuits for a short to ground. If both signal circuits test normal, replace the K20 ECM.
3. Test for 1,850-3,000 mV between the high signal circuit terminal listed below and ground.
* B52 HO2S 1 high signal terminal 4
* B52 HO2S 2 high signal terminal B
• If less than the specified range, test the high signal circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the high signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
4. Connect a 3 A fused jumper wire between the high signal circuit and low signal circuit terminals listed below:
* B52 HO2S 1 high signal circuit terminal 4 to low signal circuit terminal 3
* B52 HO2S 2 high signal circuit terminal B to low signal circuit terminal A
Note: The low signal circuit is tied to a pull-up circuit within the ECM. A voltage of 0-1,100 mV on the low signal circuit is normal.
5. Verify the scan tool HO2S 1 or 2 voltage parameter displays 0.0 mV.
• If greater than the specified range, test the low signal circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
6. Verify none of the following conditions exist:
* Lean or rich fuel injectors-Refer to Fuel Injector Solenoid Coil Test Fuel Injector Solenoid Coil Test
* Water intrusion in the B52 HO2S harness connector
* Low or high fuel system pressure-Refer to Fuel System Diagnosis Fuel System Diagnosis
* Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis Testing and Inspection
* Fuel saturation of the evaporative emission (EVAP) canister
* Exhaust leaks
* Engine vacuum leaks
* Engine oil consumption-Refer to Oil Consumption Diagnosis Oil Consumption Diagnosis
* Engine coolant consumption-Refer to Loss of Coolant Loss of Coolant
• If you find any of the above conditions, repair as necessary.
7. If all circuits test normal, test or replace the appropriate B52 HO2S.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* 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 Programming and Relearning for ECM replacement, setup, and programming