X87 - Check HO2S Circuit For Short to Power

- Key "OFF".

- Left or Front Heated Oxygen Sensor (HO2S) disconnected.

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

- Key "ON".

Oxygen Sensor Connector:

- Measure voltage between the HO2S signal at the HO2S vehicle harness connector and chassis ground.

- Is voltage less than 1.0 volt?

Yes -- Replace PCM. Reconnect HO2S. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)

No -- Service short circuit. Reconnect PCM and HO2S. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)