BMW 6 Series Exhaust Leak Nightmare: Real Help Needed

Hey there! I had nearly identical issues with my 2019 BMW 5 series last year. The symptoms matched yours exactly, rough idle, poor acceleration, and failed emissions. Lambda sensor turned out to be the culprit. Initially, I thought it was something major, but the diagnostic showed the Lambda sensor had degraded and wasn't reading oxygen levels correctly. The repair involved replacing both upstream and downstream sensors since they work as a pair. It was a straightforward fix that took about 2 hours at the shop. This might not be your only issue given the visible exhaust leaks you mentioned. Could be worth checking your exhaust manifold gaskets too. These problems tend to compound each other, a bad sensor can make the engine run rich, which stresses other components. My advice? Get a proper diagnostic scan first. Ask the mechanic to show you the sensor readings. Any reputable shop should be willing to explain what they're seeing in the data. This wasn't a serious repair in terms of engine damage, but it definitely needed fixing to prevent worse problems down the line. Hope this helps with your situation.

Thanks for sharing your experience! That's really helpful and sounds very similar to what I'm dealing with. Just wondering, do you remember roughly how much you ended up paying for the Lambda sensor replacement? Also, have you had any other issues pop up since getting it fixed? The scanning advice makes a lot of sense, I'll definitely ask about those sensor readings when I take it in.

Hey again! Just wanted to follow up, after getting the Lambda sensor replaced for 375€, my car's been running perfectly. The exhaust treatment malfunction warning completely disappeared, and I haven't had a single issue since. What a relief it turned out to be just the Lambda sensor! The throttle response is back to normal, and that annoying rough idle is gone. Best money I've spent on the car, honestly. The mechanic showed me the diagnostic readings before and after, and the difference was like night and day. I know how nerve-wracking these issues can be, especially with a BMW, but sometimes it's just a simple fix. Make sure you get those sensor readings checked like I mentioned before, it'll save you from throwing money at the wrong problem. Let me know how it goes with your car. Fingers crossed it's the same straightforward fix as mine was!

Update on my BMW situation, finally got it sorted! Took your advice and went to a new mechanic who did the diagnostic scan. You were spot on, it was indeed the Lambda sensor causing most of the trouble. Also found a small crack in the exhaust manifold gasket, just like you mentioned might be the case. Total bill came to a bit more than yours, about 650 for both issues, but honestly, worth every penny. The car's running like new now. No more rough idle, power's back to normal, and that awful exhaust smell is gone. Such a relief it wasn't something more serious! Thanks so much for sharing your experience, really helped me feel more confident about handling the situation. I actually showed the mechanic those sensor readings you mentioned, and he was impressed I knew to ask about them. Definitely learned my lesson about getting proper diagnostics done first. Really appreciate everyone's help on this. Going to stick with this new mechanic too, what a difference dealing with someone who actually explains what they're doing!