Circuit/System Testing
- Ignition OFF, disconnect the harness connector of the HO2S 1.
- Ignition ON, verify that the HO2S 1 parameter is between 350-500 mV.
- If greater than 500 mV, test the signal circuit of the HO2S sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Connect a test lamp between the low reference circuit of the HO2S sensor and B+.
- Ignition ON, test for less than 0.1 volt between the low reference circuit of the HO2S sensor and ground.
- If greater than 0.1 volt, test the low reference circuit of the HO2S for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
- Verify that none of the following conditions exist:
- Rich fuel injectors-Refer to Fuel Injector Balance Test with Special Tool .
- Water intrusion in the HO2S harness connector
- 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 near the HO2S
- Contaminated HO2S-Silicon
- If you find any of the above conditions, repair as necessary.
- If all circuits/connections test normal, replace the HO2S.
IMPORTANT:
The test lamp is used to load the circuit and may not illuminate.