OBD-II FAULT CODE
P0478
Exhaust Pressure Control Valve High
Meaning, symptoms, likely causes, diagnostic checks and repair guidance for P0478.
- Check Engine light
- Poor drivability or reduced fuel economy depending on fault
- High signal voltage
- Open ground
- Short to voltage
- Failed sensor
- Scan all modules and record freeze-frame data before clearing codes
- Check battery voltage and related fuses
- Check sensor ground and signal circuit for short to voltage
- Repair ground/signal circuit or replace confirmed faulty sensor
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Disclaimer: Information is provided for general guidance only and may not apply to all vehicles. Always consult a qualified technician.