P3034moderate severityPowertrain
Supercharger Bypass Actuator Circuit Open
on 2004 Audi TT 3.2L VR6 · AWD
What this code means
The supercharger bypass actuator that controls airflow around the supercharger for efficiency is not responding due to an open circuit.
Symptoms
- Check Engine Light
- Supercharger always pumping air (no bypass)
- Higher parasitic load on engine
- Reduced fuel economy at cruise
- Supercharger whine present at all times
Common causes
- Bypass actuator motor open circuit
- Wiring harness disconnected
- Connector pin backed out
- Actuator failed internally
- PCM driver circuit blown
Diagnostic steps
- Test bypass actuator motor resistance
- Check wiring continuity to actuator
- Inspect connector for backed-out pins
- Command actuator via scan tool
- Measure PCM output voltage at actuator
Repair notes
Replace supercharger bypass actuator or repair wiring. Verify bypass operates correctly at low load conditions.
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