7F Hex

Right Bank Downstream HO2S Shorted To Voltage:

Trouble Code Number
- Scan tool 127
- General scan tool P0158
- MIL 21

Fault Message
- Right bank Downstream HO2S Shorted to Voltage

Background
- Right bank downstream heated oxygen sensor requires a heater circuit for proper operation.
- The heater circuit is supplied with battery voltage through the MFI relay (ASD relay).
- A failure in the sensors heater circuit prevents it from providing accurate data to the PCM.
- If the PCM monitors more than 1.2 volts, the sensor has shorted to heater circuit voltage.

Range of Check
- 2 or more minutes after engine starts
- Engine coolant temperature: 80°C (176°F) or more

Set Condition
- Heated oxygen sensor output voltage is more than 1.2 V for 3 seconds.

Probable Cause
- Right bank downstream heated oxygen sensor failed
- Wiring harness and connectors failed
- PCM failed