P2590: Turbocharger Boost Control Position Sensor B Circuit Intermittent/Erratic
What to do
The car will mostly feel normal, with occasional flat spots or a warning light that comes and goes.
Note when it happens and say so — a fault that appears after a long climb or a sustained fast run and clears once the engine has cooled points at heat affecting a connector or the wiring, which is a much smaller job than anything involving a turbocharger.
Worth acting on rather than waiting for it to become permanent. This is often the early stage of carbon stiffening the vane mechanism, and a mechanism that is still stiff rather than seized can often be freed off instead of replaced. On a car with two turbochargers it is also the moment to have both checked — they have done the same miles, and doing both at once is one job rather than two.
What this code means
The second turbocharger's vane position signal drops out or jumps rather than moving smoothly, and recovers.
The physical explanation is the one given at P2566: the sensor is bolted to something that gets extremely hot and then cools, over and over. Connectors that are merely tight rather than latched work loose as metal expands and contracts, and hardened insulation opens a crack when hot that closes as it cools. So the fault is often present only after the engine has worked hard, and absent by the time the car reaches a workshop — which makes the driver's account of when it happens more useful than anything a stationary test will show.
The other genuine cause is mechanical: vanes that are stiff rather than seized move raggedly, so the signal is honest and the movement itself is erratic. That is the early stage of the carbon problem described at P2563, and it is much cheaper to catch here than later.
On a twin-turbo engine, an intermittent code on one side is a reason to look at both. Both mechanisms have accumulated carbon on the same journeys, and the one that is merely stiff today is the one that seizes next. It is the point at which freeing both off is a single job rather than two.
Likely causes
Start here
- Intermittent wiring fault · moderate
- Corroded or loose connector · easy
- Heat damage to sensor or wiring · moderate
Less common
- Carbon build-up seizing the turbocharger vanes · specialist
- Faulty turbocharger vane position sensor · moderate
Symptoms
Components involved
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.
Community experience
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