Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the HO2S 1.
- Ignition ON, test for 350-550 mV between the high signal circuit terminal 1 and the low signal circuit terminal 5.
- If less than the specified range, test the low signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, replace the HO2S 1.