P0653moderate severityPowertrain
Sensor Reference Voltage B Circuit High
on 2009 Audi A8 4.2L V8 · AWD
What this code means
The PCM detected a high voltage condition on the B sensor reference voltage circuit. This may cause several sensors to report faulty readings.
Symptoms
- Multiple sensor codes
- Rough running engine
- Check engine light on
Common causes
- Short to voltage in reference circuit
- Open ground in circuit
- Damaged wiring or connector
- PCM internal fault
Diagnostic steps
- Scan stored codes
- Check circuit for short to power
- Verify sensor grounds
- Test PCM reference voltage
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