H21 - Check For Power at HO2S Harness Connector

- Key "ON", engine "OFF".

- Heated Oxygen Sensor (HO2S) disconnected.

- Measure voltage between KEY POWER circuit and PWR GND circuit at the HO2S vehicle harness connector (refer to schematic). H - Test Schematic

- Is voltage greater than 10.5 volts?

Yes -- Go to H22. H22 - Check Continuity of Power Ground Circuit

No -- Service open in KEY PWR circuit. Reconnect HO2S. Rerun Quick Test. Quick Test Appendix (Detailed Testing Instructions)