What does code P0478 mean?
The control signal to the exhaust pressure control valve is higher than expected.
OBD-II Code
P0478 — Exhaust Pressure Control Valve High
The control signal to the exhaust pressure control valve is higher than expected.
Common symptoms
- Overpressure condition
- limp mode activation
Possible causes
- Short to voltage
- stuck solenoid
Initial recommendation
Inspect wiring for voltage shorts and replace exhaust pressure control valve if faulty.
Safety notice
This information is for guidance only and does not replace a physical vehicle inspection or diagnosis by a qualified mechanic. If the vehicle has severe power loss, smoke, a fuel odor, overheating, brake or steering problems, or any unsafe behavior, avoid driving it and seek professional inspection.
Analyze this code with MecaOBD
Use the app to combine code P0478 with your vehicle's actual symptoms for more complete diagnostic guidance.
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