BMW 320d Turbo Trouble: Whistling Sound and Power Loss

Hey there! I had almost identical issues with my BMW 518d (2012) last year. The symptoms you're describing match exactly what I experienced, whistling noise, power loss, and that annoying check engine light. Turned out to be a faulty wastegate valve in my case. The wastegate wasn't regulating boost pressure properly, which explained the power loss and strange noises. It's definitely a serious issue that needs sorting soon, as it can potentially damage your turbo if left unchecked. When I took mine in, the diagnostic confirmed the wastegate actuator had worn out. The mechanic showed me how the rod had excessive play, causing irregular boost pressure. They had to replace the entire wastegate assembly to fix it. Since getting it fixed, the car's been running like new, no more whistling, proper power delivery, and fuel consumption back to normal. Best to get it checked soon before it causes more issues with the turbo system. One tip: make sure they perform a proper boost pressure test before and after the repair to confirm everything's working correctly.

Thanks so much for sharing your experience! This sounds exactly like what I'm dealing with. The wastegate issue makes total sense given all the symptoms. I was a bit worried it might be the entire turbo needing replacement. Can't remember if you mentioned it, how much did the wastegate replacement set you back? Also, curious to know if you've had any other boost-related problems since getting it fixed? Really want to avoid any surprises when I take it to the shop.

Hey again! Glad I could help out! Actually, I just got the car back from the mechanic last week after dealing with that wastegate issue I mentioned. Had to shell out 860 € for the repair, but honestly, it was worth every penny. The car's running absolutely perfect now, no more weird noises or power problems. Haven't had a single boost-related issue since they fixed it. The mechanic did a really thorough job replacing the defective wastegate valve and ran complete pressure tests afterward to make sure everything was spot-on. Fuel consumption's back to normal too, which is a nice bonus. Just make sure whoever works on yours knows their way around BMW turbos, it's not the most complicated fix, but you definitely want someone who knows what they're doing. The boost pressure system's all good now, and the engine's running as smooth as butter. Trust me, you'll feel the difference as soon as they fix it! Let me know how it goes when you get yours sorted. Always happy to help out a fellow BMW owner!

Thanks for all the details! I finally got my car sorted at the mechanic yesterday. You were absolutely right about the wastegate, that was exactly the problem. Ended up paying a bit more than you did, around 950 €, but the difference in how the car runs now is like night and day. The mechanic I found was really knowledgeable about BMWs. He showed me the old wastegate and it was in terrible shape! No wonder I was having all those issues. They did a complete pressure test after the fix, just like you suggested. Took it for a proper drive today and couldn't be happier. The whistling's completely gone, power delivery is smooth again, and the engine light's finally off. Feels like I got my car back! Really glad I didn't wait any longer to get it fixed. Thanks again for steering me in the right direction with this. You saved me a lot of worry and probably some money too by helping me pinpoint the issue before going to the shop.