Third O2 sensor (where equipped) circuit high — some V engines use multiple upstream sensors.
Common symptoms
- Check engine light
- Fuel trim issues
Typical causes
- Failed O2 sensor
- Open circuit
- Exhaust leak affecting sensor
What scanner do you need?
Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)
Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.
Diagnostic tips
- Record freeze frame data when the code first sets
- Clear the code only after fixing the root cause
- Check for related pending codes that point to a common issue
- Verify battery voltage is above 12.4V before chasing sensor codes