P049F
Exhaust Pressure Control Valve B
A general circuit fault is detected on the second exhaust pressure control valve (B) - used for example on dual exhaust brakes, twin-bank diesels with separate back-pressure flaps, or for DPF regeneration backpressure assist on the second bank. The ECU loses control of this stage.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Open in harness or actuator windingCommon
- Connector corroded by exhaust heat or moisturePossible
Parts involved
- Exhaust Pressure Valve B
- Exhaust Pressure Actuator B
P049F is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.