Circuit/System Testing
- Verify none of the following conditions exist:
- An exhaust leak near the HO2S-Refer to Symptoms - Engine Exhaust .
- Lean or rich fuel injectors-Refer to Fuel Injector Balance Test with Special Tool .
- The HO2S is not securely installed.
- Water intrusion or corrosion in the HO2S harness connector
- Poor terminal tension at the HO2S and at the ECM
- HO2S wiring harness damage
- 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 EVAP canister
- Engine vacuum leaks
- Incorrect RTV sealant
- Engine oil consumption-Refer to Symptoms - Engine Mechanical .
- Engine coolant consumption-Refer to Loss of Coolant .
- If you find any of the above conditions, repair as necessary.
- If all conditions test normal, test or replace the appropriate HO2S.