P0134

DTC P0134 or P0154

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptors
DTC P0134
- HO2S Circuit Insufficient Activity Bank 1 Sensor 1

DTC P0154
- HO2S Circuit Insufficient Activity Bank 2 Sensor 1




Diagnostic Fault Information






Typical Scan Tool Data






Circuit 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. The control module supplies the HO2S with a reference, or bias voltage of about 450 mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. 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 above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage 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 DTCs

* DTC P0116, P0117, P0118, P0119, P0201, P0202, P0203, P0204, P0205, P0206, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, or P0277 is not set.
* The ignition voltage is greater than 10 volts.
* The engine is operating for greater than 1 second.
* The HO2S heater is active for greater than 25 seconds.
* The HO2S is at operating temperature for greater than 30 seconds.
* The primary HO2S heater duty cycle is greater than 68 percent.
* The calculated exhaust temperature is between 600-800°C (1112-1472°F).
* DTCs P0134 and P0154 run continuously once the conditions above exist for greater than 5 seconds.



Conditions for Setting the DTCs

* A primary HO2S voltage is between 400-600 mV.
* The calculated internal resistance of a primary HO2S is greater than 20,000 ohms when the calculated exhaust temperature is greater than 600°C (1112°F).
* A corresponding primary and secondary HO2S are greater than 200 mV during a decel fuel cut-off.
* DTC P0134 or P0154 set if any of the conditions above exist for greater than 4 seconds or for a cumulative of 50 seconds.



Action Taken when the DTC Sets

DTCs P0134 and P0154 are Type B DTCs.


Conditions for Clearing the MIL/DTC

DTCs P0134 and P0154 are Type B DTCs.


Reference Information
Schematic Reference

Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Engine idling, observe the HO2S voltage parameter. The voltage should fluctuate above and below the range of 350-550 mV.
2. 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 HO2S.
2. Ignition ON, test for B+ on the HO2S ignition voltage circuit terminal C of the HO2S harness connector.

• If less than the specified value, repair the ignition voltage circuit for an open/high resistance.

3. Ignition OFF, connect a test lamp between the heater control circuit terminal D and B+.
4. Idle the engine, and verify the test lamp illuminates or flashes with bright intensity.

• If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

5. Ignition ON, verify that the applicable HO2S voltage parameter is between 350-500 mV.

• If less than the specified range, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.


• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

6. Install a 3A fused jumper wire between the signal circuit terminal B and ground. Verify the HO2S voltage parameter is less than 60 mV.

• If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

7. Connect a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the HO2S voltage parameter is less than 60 mV.

• If greater than the specified range, test the low reference circuit for an open/high resistance or for a short to voltage. If the circuit/connections test normal, replace the ECM.

8. Verify that none of the following conditions exist:

* The HO2S is loose
* Lean or rich fuel injectors-Refer to Fuel Injector Balance Test with Special Tool (Fuel Injector Balance Test With Special Tool) or Fuel Injector Balance Test with Tech 2 (Fuel Injector Balance Test With Tech 2) .
* Water intrusion in the HO2S harness connector
* Low or high fuel system pressure-Refer to Fuel System Diagnosis (Component Tests and General Diagnostics) .
* Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) (Alcohol/Contaminants-In-Fuel Diagnosis (With Special Tool)) .
* 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.


9. If all circuits/connections test normal, replace the applicable HO2S.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (Service and Repair)
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming