Mini Paceman Diesel Engine Problem

Sounds like you're having boost issues. I had something similar happen with my Mini, though I can't remember the exact mileage. Check your pressure sensor and the throttle body connections. A leak in the boost control system can cause all those symptoms.

Thanks for the quick reply! When you mention checking the pressure sensor and throttle body connections, what exactly am I looking for? Is it like checking a hose for leaks on a garden hose or something?

Yep, think garden hose analogy is good. A split hose or loose connection there will drop pressure. For me, it turned out to be a faulty wastegate valve on the turbocharger itself. Workshop confirmed it with a scan, and they said it's a common issue. I'd advise getting it checked out professionally.

Just wanted to close the loop on this. Took it to a trusted workshop, and they confirmed it was indeed the wastegate valve. They replaced it, and the whistling is gone, the check engine light is off, and the power is back! Cost me around 860€, but well worth it to have my Paceman running smoothly again. Thanks for your help!