Seat Leon engine issues

That sounds suspiciously like what happened with my old Volvo V70! The engine light, the jerking, the whistling...it was a nightmare. Have you checked the air intake hose for any cracks or loose connections? Sometimes a small leak there can cause similar symptoms, messing with the pressure readings the boost sensor is getting. Think of it like trying to blow up a balloon with a tiny hole in it – the pressure just won't build up correctly. Could also be the pressure sensor itself or a wire going to it. Have you scanned it for any error codes?

Thanks for your quick reply! I checked the hoses connected to the air intake, but I did not find any obvious cracks, but to be honest I am a complete novice. Where exactly is the boost sensor located in the intake manifold, and how can I check the cable connection? I do not have any OBD scanner myself. Is it still safe to drive to the nearest workshop?

Okay, since you're not comfortable poking around too much, and you don't have a scanner, I would advise against driving it too far. The engine light and stalling could indicate a more serious issue than just a loose connection, potentially damaging the catalytic converter. In my case with the Volvo, I ended up causing more harm than good by driving it with the faulty sensor. It's most likely the boost sensor or its connection, as you suspected, which is plausible given the symptoms. A workshop can quickly diagnose it, and the sensor itself is not that expensive. It will be a quick fix for them.

Thank you very much for your quick help and assessment! I followed your suggestion and took my Leon to the workshop. You were spot on, it was indeed the boost pressure sensor and a defective cable. They replaced it for 95€, and the car is running smoothly again. I really appreciate your help!