P0478
Exhaust Pressure Control Valve A High
P0478 is an OBD-II diagnostic trouble code meaning: Exhaust Pressure Control Valve A High. Common causes: short circuit in valve control circuit, faulty exhaust gas pressure control valve. Estimated repair cost: $56–167.
Symptoms
- Check Engine Light Is On
- Deterioration of vehicle dynamics
- Increased fuel consumption
- Unstable engine operation
Causes
- Short circuit in valve control circuit
- Faulty exhaust gas pressure control valve
- Wiring harness damage
- Problems with the engine ECU
How to Fix
- Check the wiring harness for damage
- Check the resistance of the exhaust gas pressure control valve
- Check control circuit for short circuit
- If necessary, replace the valve or repair the wiring harness
- Clear the error and check if it appears again
Related codes
Error P0478 by Vehicle Brand
FAQ
What does the P0478 code mean?
P0478 is an OBD-II diagnostic trouble code that indicates: Exhaust Pressure Control Valve A High
What causes a P0478 error code?
The most common causes of P0478 include: Short circuit in valve control circuit; Faulty exhaust gas pressure control valve; Wiring harness damage; Problems with the engine ECU.
How do I fix a P0478 diagnostic trouble code?
To fix P0478: Check the wiring harness for damage. Check the resistance of the exhaust gas pressure control valve. Check control circuit for short circuit. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P0478?
Limited driving only, diagnose soon
How much does it cost to fix P0478?
The estimated repair cost for P0478 is $56–167. Actual cost depends on your vehicle, location, and labor rates.
See also: Russian version · NationStat