BMW 1 Series Diesel: Boost Issue Causes Power Loss

Hey there! I've got some experience working on cars and dealt with almost identical issues on my 2013 BMW 3 series diesel last year. The symptoms you're describing sound exactly like what I experienced with my car, that whistling noise during acceleration was particularly familiar! After struggling with it for a few days, I took it to my regular workshop. Turned out the wastegate valve was faulty, causing boost pressure problems. The repair set me back about 860 Euro, but it fixed all those issues, the power loss, stalling, and that annoying whistle completely disappeared. Before jumping to conclusions though, could you share some more details? What's your current mileage, and have you noticed any other warning messages besides the engine light? Also, have you had any recent work done on the turbo system? I really recommend getting this checked soon, running with boost issues can lead to bigger problems if left unchecked. If it turns out to be the same problem I had with my 3 series (and it really sounds like it is), at least you'll have an idea of what to expect cost-wise.

Thanks for sharing your experience! My car has 6178 KM on the clock, and it's been regularly serviced. Actually, I noticed these symptoms right after my last service about two weeks ago. Haven't had any other warning lights besides the engine light, and no previous work done on the turbo system. Really appreciate the heads up about the wastegate valve, that's definitely something I'll have them check out first. Planning to take it to the shop tomorrow morning since I don't want to risk any further damage.

Hey again! Thanks for the additional info about your mileage and service history. You know what, that timing after the recent service really rings a bell for me. When I had my 3 series issue, it also started acting up shortly after routine maintenance. In my case, turns out the technician had actually disturbed some connections while doing other work. The wastegate actuator wasn't properly reseated after they were poking around in there. That might explain why you're seeing these issues on such low mileage. For reference, my car had around 95,000 KM when this happened, so yours being much newer makes me think it's probably not normal wear and tear like mine was. Definitely mention to your mechanic that these issues started right after the service, could save them some diagnostic time and you some money. Just a quick tip from my experience, make sure they check all the boost pressure connections and hoses while they're at it. Sometimes it's not just the wastegate but also loose clamps or small cracks in the pipes that can cause similar symptoms. Would hate for you to replace parts unnecessarily like I almost did! Let us know what they find. Really curious to see if it's something simple like a loose connection from the service.

Thanks so much for the detailed follow-up! You've actually made me feel a lot better about this whole situation. I'll definitely mention the service timing when I take it in tomorrow, that's such a good point about possible disturbed connections. I was honestly worried I'd need a whole new turbo system, but hearing about your experience with similar symptoms makes me hopeful it might be something simpler. I've just called the workshop and managed to get an early slot tomorrow. I'll make sure they check all those boost pressure connections and hoses you mentioned, not just the wastegate. It's great to have this info before going in, feels like I can have a more informed conversation with the mechanic now. Will definitely update this thread once I know what's actually causing the problem. Really appreciate you taking the time to share your experience!