P04A4Exhaust Pressure Control Valve B Stuck Open
The exhaust pressure control valve B is mechanically stuck in the open position. The ECU commands closing for back-pressure assist or exhaust braking, but the position feedback shows it remains open - typically heavy soot, broken linkage, or a sticky valve shaft.
Can I keep driving? With caution
You can drive to the shop, but do not postpone the repair. The problem may worsen and damage other components.
Sistema Afectado
Sistema de Escape · Catalizador y sensores O₂
La falla se localiza en la línea de escape: catalizador, sondas lambda (O₂) o sistema EGR.
Espacio para vendedores de repuestos
Aún no hay un anunciante en este espacio.
Possible Causes
The components or conditions that trigger this code
- 1Valve stuck open due to soot or broken linkage Carbon or debris buildup preventing free movement Component wear with age - mechanical play
How to Fix It — Step by Step
Recommended diagnostic and repair procedure
- 1Difficulty: medium. Estimated time: 1.5-4 hours. Estimated cost: €250-€
- 2Professional repair recommended
Note: This information is for general reference. For precise diagnostics and safety repairs, always consult a certified mechanic.
Estimated Cost
Approximate range in USD (varies by region and shop)
Varies by diagnosis
* Diagnosis only: $50–$150
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