H19 - Check HO2S For Short to Ground

- Key "OFF".

- Breakout box installed, Powertrain Control Module (PCM) disconnected.

- Heated Oxygen Sensor (HO2S) disconnected.

- Measure resistance between PWR GND and HO2S circuit at the HO2S connector.

- Measure resistance between HO2S circuit and HO2S GND and/or SIG RTN at the HO2S connector. H - Test Schematic

- Is resistance greater than 10,000 ohms?

Yes -- For Diagnostic Trouble Codes (DTC): 136, 139, 144, 171, 172, 175 or 176, go to H20. H20 - Check Resistance of Heated Element on HO2S
No -- Replace HO2S. Remove breakout box. Reconnect PCM. Drive vehicle 5 miles/55 mph. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)