P2587: Turbocharger Boost Control Position Sensor B Circuit Range/Performance
What to do
Read P2563 before authorising anything — it explains why this family of codes names the turbocharger while the actual fault is usually carbon binding the vanes, or the actuator that moves them, both far cheaper to put right.
One thing to ask for that is specific to a twin-turbo car: have both turbochargers' vane mechanisms been checked, not just the one that set the code? They have done the same mileage in the same conditions, so if one has stiffened with carbon the other very likely has too. Freeing both off while the engine is open costs far less than doing the same job twice a few months apart, and finding the second one stiff is common.
Also worth reporting: whether the problem is there all the time or only at higher speeds. On a car with a small and a large turbo working in sequence, symptoms that only appear on the motorway point specifically at the second unit.
What this code means
The second turbocharger's vane position signal is electrically valid and does not match what was commanded. The module asked for a position and the vanes did not arrive there.
Everything that makes P2563 the most expensively misread code in diesel diagnostics applies here without modification. The turbocharger is named and the turbocharger is usually not what is wrong: carbon accumulating on the vane pivots and the unison ring stiffens and then binds the mechanism, the actuator pushes, the vanes fall short, and the sensor honestly reports where they got to. Read P2563 for the full diagnostic order — actuator and linkage, then the vane mechanism, then calibration, then the turbocharger last.
What is worth adding here is the comparison the second turbocharger makes possible, and it is genuinely useful. A twin-turbo vehicle has two of these mechanisms living in the same exhaust environment, doing similar work, of similar age. So the healthy one is a reference for the sick one. Commanding both through their full travel and comparing the position feedback side by side separates a mechanism that has coked up from a sensor or actuator that has failed electrically, in a way a single-turbo vehicle cannot offer.
It also raises the question worth asking before a repair is authorised: if one has coked up on a given set of journeys, the other has had exactly the same journeys. Finding the second stiff but not yet setting a code is common, and it is far cheaper to free both off while access is open than to do the job twice.
Which way the vanes are stuck is still readable from the driving, as at P2563 — stuck closed gives strong low-speed boost then a sudden cut to limp mode, stuck open gives nothing low down and black smoke. On a sequential system, symptoms confined to higher engine speeds point at the second unit specifically.
Likely causes
Start here
- Carbon build-up seizing the turbocharger vanes · specialist
- Faulty turbocharger vane actuator · specialist
- Leaking or perished vacuum hose · easy
Less common
- Actuator not calibrated after repair · specialist
- Faulty turbocharger vane position sensor · moderate
- Damaged actuator linkage · moderate
- Worn turbocharger bearings · specialist
Symptoms
Components involved
Information, not instruction
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Community experience
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