Cause
Wastegate stuck open or closed
A wastegate jammed at one end of its travel, so boost control is lost in one direction. Naming both directions together is deliberate — the mechanism and the causes are identical, and only where it stopped decides which symptom the driver reports.
Stuck open, exhaust permanently bypasses the turbine and the engine underboosts. The complaint is a general lack of power with a turbocharger that is mechanically fine. Stuck closed is the dangerous direction: nothing limits the turbine, boost climbs past its target, and the module will cut fuelling or power to protect the engine — so the complaint is a sudden and repeatable loss of power under hard acceleration rather than a constant one.
A vacuum or electric actuator that tests correctly points at the valve. Disconnect it and check the arm moves fully and freely by hand; carbon on the seat, corrosion on the shaft, or a bent linkage are what hold it. On a variable-geometry turbocharger the equivalent is the vane mechanism, which seizes the same way and produces the same pair of symptoms.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
2 of the 4 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (4)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2263 Turbocharger/Supercharger A Boost System Performance Likely for this code High
- P2262 Turbocharger/Supercharger Boost Pressure A Not Detected — Mechanical High
- P2579 Turbocharger/Supercharger Speed Sensor A Circuit Range/Performance Stop driving High
- P2594 Turbocharger Speed Sensor B Circuit Range/Performance Stop driving High
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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