Circuit/System Verification

Ignition ON.
Verify no HO2S heater DTCs are set
- If a HO2S heater DTC is set
  Refer to DTC P0131, P0132, P0134, P0137, P0138 or P0140 .
- If no HO2S heater DTC is set
Allow the engine to reach operating temperature, engine running.
Verify the scan tool HO2S Sensor 1 or 2 voltage parameters are between 50-1, 050 mV.
- If not between 50-1, 050 mV
  Refer to DTC P0131, P0132, P0134, P0137, P0138 or P0140 .
- If between 50-1, 050 mV
Verify none of the following conditions exist:
- Lean or rich fuel injectors
- Water intrusion in the HO2S harness connector
- Low or high fuel system pressure-Refer to Fuel System Diagnosis .
- Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- Fuel saturation of the evaporative emission (EVAP) canister
- Exhaust leaks
- Engine vacuum leaks
- Engine oil consumptions-Refer to Symptoms - Engine Cooling .
- Engine coolant consumption-Refer to Symptoms - Engine Cooling .
- If any of the above conditions exist
  Repair as necessary.
- If none of the above conditions exist
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.
Verify the DTC does not set.
- If the DTC sets
  Replace the B52 Heated Oxygen Sensor.
- If the DTC does not set
All OK.