Check HO2S (S1)
- Substitute with a known-good HO2S (S1) and check for proper operation.
- Is the signal normal?
YES
- Replace the HO2S (S1) with an usable one and check for proper operation. If the problem is corrected, replace the HO2S (S1) and then go to "Verification of Vehicle Repair ".
NO
- Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector. Or, ECM memory was not cleared after repair. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair ".