P2CB8
Turbocharger/Supercharger Boost Pressure B Too High – Mechanical
The boost pressure on branch B exceeds the calibrated maximum. Mechanical fault — wastegate stuck closed or boost control valve jammed.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Common causes
Ordered by how often each turns out to be the cause.
- Wastegate stuck closedCommon
- Boost control valve jammedPossible
Parts involved
- Turbocharger B
- Wastegate B
- Boost Pressure Sensor B
P2CB8 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.