P259E
Turbocharger A Boost Control Position At Low Limit
The boost-control actuator on turbo A has been operating at the low end of its travel for too long — the closed-loop controller is saturated against the lower stop trying to reach the boost setpoint. Indicates either a leak (wastegate held closed but boost still escapes) or commanded boost above what the engine can produce.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
Common causes
Ordered by how often each turns out to be the cause.
- Boost leak in the charge-air pathCommon
- Failing turbocharger that cannot produce target boostPossible
Parts involved
- Turbo Actuator A
- Boost Control Loop
P259E 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.