P2566: Turbocharger Boost Control Position Sensor A Circuit Intermittent
What to do
The car will mostly feel normal, with occasional flat spots or a warning light that comes and goes. Pay attention to 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 the 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 sometimes be freed off instead of replaced.
What this code means
The vane position signal drops out or jumps rather than moving smoothly, and recovers.
Intermittent faults in this location have a physical explanation that is easy to test for and easy to overlook: the sensor is bolted to something that gets extremely hot and then cools, over and over. Metal expands, connectors that are merely tight rather than properly latched work loose, and insulation that has hardened cracks open when hot and closes again when cold. So the fault is often present only when the engine has been working hard, and absent by the time the car reaches a workshop.
The pattern the driver notices is therefore diagnostic and worth reporting: power that disappears on a long climb or a motorway run and returns after the engine cools points at a heat-related connection, not at a failing turbocharger.
The other genuine cause is mechanical: vanes that are stiff rather than seized move raggedly, so the position signal is honest and the movement itself is erratic. That is the early stage of the carbon problem described at P2563, and catching it there is considerably cheaper than catching it later.
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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