Error code
OBD2 P0478
OBD2P0478
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.
What it means
Exhaust Pressure Control Valve High.
Severity
moderateCan be driven, but may experience reduced performance and fuel efficiency.
Summary
P0478 indicates an issue with the exhaust pressure control valve, specifically that it is receiving too high of an input signal from the ECM.
Common Causes
- Wiring short to positive
- Faulty exhaust gas pressure control valve
Fixes
- Replace the faulty exhaust gas pressure control valve.
FAQ
What does P0478 mean?
P0478 indicates an issue with the exhaust pressure control valve receiving too high of an input signal from the ECM.
How do I fix P0478?
The most common solution is to replace the faulty exhaust gas pressure control valve. It's recommended to consult a professional mechanic for proper diagnosis and repair.
Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
More OBD2 codes
- P0400Exhaust Gas Recirculation Flow
- P0401Exhaust Gas Recirculation Flow Insufficient Detected
- P0402Exhaust Gas Recirculation Flow Excessive Detected
- P0403Exhaust Gas Recirculation Control Circuit
- P0404Exhaust Gas Recirculation Control Circuit Range/Performance
- P0405Exhaust Gas Recirculation Sensor 'A' Circuit Low
- P0406Exhaust Gas Recirculation Sensor 'A' Circuit High
- P0407Exhaust Gas Recirculation Sensor 'B' Circuit Low
- P0408Exhaust Gas Recirculation Sensor 'B' Circuit High
- P0409Exhaust Gas Recirculation Sensor 'A' Circuit
- P0410Secondary Air Injection System
- P0411Secondary Air Injection System Incorrect Flow Detected