Exhaust Pressure Control Valve B Stuck Closed
Same as P04A4 but the valve B is stuck closed - back-pressure stays high even when the engine should run with low restriction; risk of overheating or excessive fuel consumption.
Affected components
- Exhaust pressure valve b
Common causes
- High likelihood: Valve stuck closed due to soot or broken linkage
- Low likelihood: Carbon or debris buildup preventing free movement
- Low likelihood: Component wear with age - mechanical play
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.