BMW X6 Diesel: Boost System Failure Warning Signs

Hey there! I had pretty similar issues with my 2019 BMW X5 diesel last year (I've got some experience working on cars, but mainly basic maintenance stuff). Those symptoms sound very familiar, my X5 was doing almost exactly the same thing. Turned out to be a faulty wastegate valve that was stuck partially open. I initially thought about checking it myself but took it to my regular workshop since turbo-related issues can be tricky. They diagnosed and replaced the wastegate valve, which set me back about 860 Euro. After the fix, the car ran like new again, no more whistling, power was back to normal, and fuel consumption went back to what it should be. Before I can give more specific advice, could you share: How many miles/kilometers are on your X6? When did these symptoms first appear? Have you noticed any blue smoke from the exhaust?

Thanks for your input! Just had my service done last month at 80350 KM. The symptoms started appearing about a week ago, and no blue smoke from the exhaust at all. The whistling noise is especially noticeable between 2000-3000 RPM. Good to hear your issue was just the wastegate valve, definitely gives me some hope it's not something more serious with the turbo itself. I'll probably have it checked by a professional since I'm not too comfortable messing with the turbo system myself. Did your repair include any other parts besides the wastegate valve?

Hey again! Yeah, with my X5, apart from the wastegate valve itself, they also replaced some gaskets and seals as a precautionary measure, it's pretty standard practice when they're already in there doing the work. The whole job took about 4-5 hours. Since your mileage is similar to what mine was when I had the issue (mine was around 85000 KM), and the symptoms are pretty much identical, especially that whistling noise in the same RPM range, I'm even more convinced it's probably the same problem. When they did mine, they actually showed me the old wastegate valve, it was pretty gunked up with carbon deposits, which is apparently quite common on these diesel engines. The mechanic mentioned it's a known wear item on these models. Here's a tip though, while you're waiting to get it into the shop, try to avoid heavy acceleration and keep the RPMs lower if possible. That's what I did after the symptoms started, just to prevent any potential additional stress on the turbo system. Better safe than sorry, you know? Just keep in mind though, prices might have gone up since I had mine done last year. But honestly, whatever the cost, it's worth getting it sorted quickly to avoid any bigger issues down the line.

Thanks so much for all the detailed info! It's really helpful knowing what to expect. I'll definitely take your advice about keeping the RPMs low until I can get it checked out, already started driving it more gently since these issues started. The fact that our symptoms match up so closely, and we've got similar mileage really does make me think it could be the same wastegate issue. I just called my regular mechanic and managed to get an appointment for next week. I made sure to mention all the symptoms and your experience with the wastegate valve, they seemed to think that's a likely culprit too. While it's not great having to spend the money, I'm actually relieved it might just be this rather than a complete turbo failure. I'll definitely have them check all the seals and gaskets too since they'll be in there anyway, just like in your case. I'll update the thread once I get it sorted to help anyone else who might run into the same problem. Really appreciate you taking the time to share your experience!