P0478 - Exhaust Pressure Control Valve A Control Valve A High

The ECM detected an exhaust pressure control valve A fault: control valve a high.

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Common Next Steps

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Related Inspection

Code Overview

The ECM detected an exhaust pressure control valve A fault: control valve a high.

Common Causes

• Failed control valve
• Damaged wiring or connector
• Restriction or mechanical sticking

Diagnostic Steps

1. Inspect the valve connector and wiring
2. Command the valve if supported and verify response
3. Inspect for restriction or soot buildup

Likely Repairs & Cost Guides

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Related OBD Codes

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Next Steps

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