P0049
Turbocharger/Supercharger A Turbine Overspeed
The turbocharger A turbine speed exceeded its safe limit. Risk of bearing damage and shaft fracture. Often caused by a stuck-closed wastegate or boost control fault.
- 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 loop faultPossible
Parts involved
- Turbocharger
- Wastegate
- Turbine Speed Sensor
P0049 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.