HB12 - Check Continuity of HO2S and HO2S Ground

- Key "OFF".

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

- Disconnect suspect Heated Oxygen Sensor (HO2S) from vehicle harness. Inspect both ends of connector for damaged or pushed out pins, moisture, corrosion, loose wires, etc. Service as necessary.

- Measure resistance between HO2S circuit test pin at the breakout box and HO2S circuit at the vehicle harness connector.

- Measure resistance between test pin 46 at the breakout box and HO2S SIG RTN at the vehicle harness connector.

- Where applicable, measure resistance between HO2S GND and SIG RTN at the breakout box.

- Is each resistance less than 5.0 ohms?

Yes -- Go to HB13. HB13 - Check HO2S Circuit For Short to Ground

No -- Service open circuit. Remove breakout box. Reconnect PCM, HO2S, and any other components that have been disconnected. Drive vehicle 5 miles/55 mph. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)