Circuit/System Testing
- Verify that none of the following conditions exist:
- Inspect the HO2S 1 and HO2S 2 for being secure
- Damaged wiring between either HO2S and the ECM
- Leaking fuel injectors-Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2
- High fuel system pressure-Refer to Fuel System Diagnosis
- Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (w/ Special Tool)
- Contaminated HO2S-Silicon
- If you find any of the above conditions, repair as necessary.
- Ignition OFF, disconnect the harness connector at the HO2S 2.
- Ignition ON, verify the scan tool HO2S 2 voltage parameter is between 350-550 mV.
- If greater than the specified range, test the HO2S 2 high signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Connect the harness connector at the HO2S 2.
- Engine idling, raise the engine speed above 1,200 RPM for 30 seconds. Verify the scan tool HO2S 2 voltage parameter is less than 1,000 mV.
- If greater than the specified range, replace the HO2S 2.
- Engine idling, move the HO2S 1 and HO2S 2 harnesses between the HO2S harness connector and the ECM. Observe the scan tool HO2S 1 lambda parameter, and the HO2S 2 voltage parameter. Verify neither parameter changes abruptly.
- If the parameter changes abruptly, repair the harness/connections as necessary.
- If all circuits/connections test normal, replace the HO2S 1.