What are the common causes of P04A5?

A stuck exhaust pressure control valve B. Carbon locking valve B closed. A failed valve B actuator. A broken valve B linkage.

Command valve B on a scan tool and watch for movement. Inspect the valve B linkage for a break. Clean carbon from valve B and its seat. Replace valve B if it stays closed at rest. Clear the code and retest.

P04A5

Exhaust Pressure Control Valve B Stuck Closed

System: Auxiliary emission controls (P code)
Lamp: Check Engine Light
Category: Powertrain - Auxiliary Emissions Controls

What it means

P04A5 means Exhaust Pressure Control Valve B Stuck Closed.

Where it lives

For P04A5, the description names the valve as the part involved.

Check these first

A stuck exhaust pressure control valve B
Carbon locking valve B closed
A failed valve B actuator
A broken valve B linkage

What to do next

Command valve B on a scan tool and watch for movement
Inspect the valve B linkage for a break
Clean carbon from valve B and its seat
Replace valve B if it stays closed at rest
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.