XB128 - Check Left HO2S Circuit For Short to Power

- Key "OFF".

- Left Heated Oxygen Sensor (HO2S) disconnected.

- Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

- Key "ON".

Oxygen Sensor Connector:

- Measure voltage between the HO2S signal at the HO2S vehicle harness connector and the battery negative post.

- Key "OFF".

- Was voltage less than 2.0 volts?

Yes -- Replace PCM. Reconnect all components. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)

No -- Service left HO2S circuit short to power. Reconnect all components. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)

Clear Keep Alive Memory. Clearing Keep Alive Memory (KAM) and Relearn Procedure