P2594
Turbocharger Speed Sensor B Circuit Range/Performance
Turbo speed sensor B is electrically intact, but the speed reading does not match the boost or air-mass model — same failure mode as sensor A performance fault, applied to the second turbo.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
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.
- Oil-contaminated sensor tipCommon
- Sensor element aged beyond calibration windowLess likely
- Sensor mounting loose - signal dampingLess likely
Parts involved
- Turbo Speed Sensor B
- Turbocharger
P2594 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.