Ford F Boost Pressure Control Fault

Sounds like a potential vacuum leak. Is the engine making any unusual noises, like a whistling or hissing sound? A faulty vacuum switching valve (VSV) can definitely cause those symptoms. When the VSV fails, the turbocharger doesn't get the correct signals. Have you checked for any obvious damage to the vacuum lines?

I haven't noticed any unusual noises. How would a defect in a vacuum switching valve lead to these issues?

The VSV controls the amount of vacuum applied to the turbocharger's wastegate. If it's faulty, the turbo might not be building boost correctly, or it might be overboosting intermittently. This causes a pressure drop, tripping the sensor, which leads to the reduced power. Best to take it to a workshop.

Thank you for the explanation. I took it to a workshop, and it was indeed a defect in a vacuum switching valve, as suggested. The repair cost 140€. The car runs smoothly again.