XB127 - Check Left HO2S For Short to Power

NOTE: Due to the internal circuitry of the Powertrain Control Module (PCM), a left Heated Oxygen Sensor (HO2S) signal short to power could produce Diagnostic Trouble Codes (DTC) 524, 542, 543.

- Key "OFF".

- Disconnect left HO2S.

Oxygen Sensor Connector:

- Measure resistance between HO2S signal pin and key power pin at the HO2S connector.

- Is resistance greater than 10,000 ohms?

Yes -- Go to XB128. XB128 - Check Left HO2S Circuit For Short to Power

No -- Replace left HO2S. Reconnect all components. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)