BMW X7 Exhaust & Performance Issues, Need Help!

Hey there! I had a similar issue with my 2018 BMW X5 last year. I've got some experience working on cars, but mainly basic maintenance stuff. My symptoms were pretty much identical, check engine light, poor acceleration, and that rough running. Took it to my trusted workshop after attempting basic checks myself. Turned out the lambda sensor was shot, which was messing with the fuel mixture and causing all those symptoms. The repair, including parts and labor, set me back 375 Euro, but it fixed everything, engine's running smooth again, no more warning lights. Before I share more specific details that might help, which engine variant do you have in your X7? Also, have you scanned for error codes? This could help narrow down if we're dealing with the same issue.

Thanks for sharing your experience! I've got the 3.0L gas engine with 24574 KM on the clock. Just had it serviced last month too. Funny you mention the lambda sensor, I was hoping it wasn't that, but the symptoms do match up pretty closely. Haven't scanned for codes yet, but I'll definitely get that done first thing. Really appreciate the repair cost info too, helps me know what I might be looking at. Did you notice any difference in fuel consumption after the repair?

Hey again! Yeah, the fuel consumption was actually one of the most noticeable improvements after fixing the lambda sensor on my X5. Before the repair, I was burning through way more fuel than usual, probably about 15-20% more than normal. Once the new sensor was in, it went right back to the usual numbers. Since you mentioned your X7 was just serviced last month, it might be worth checking if they noticed anything unusual during the service. Sometimes these issues can start small and gradually get worse. With your mileage being relatively low, it's a bit unusual for the lambda sensor to fail, but it can happen, especially if there's been any water damage or if the sensor got contaminated somehow. In my case, the rough running was most noticeable when the engine was cold, and it would smooth out a bit after warming up. Was that similar to what you're experiencing? Also, when they replaced my sensor, they found some carbon buildup in that area, which they cleaned out. Might be worth asking them to check for that too when you take it in. Let me know what the code scan shows, if it's the same codes I got, I can share some more specific details about what to expect with the repair.

Thanks so much for the detailed response! Yes, that's exactly what I'm experiencing, rougher when cold and slightly better after warm-up. Really interesting about the carbon buildup too. My fuel consumption has definitely increased lately, now that you mention it. I've scheduled a diagnostic scan for tomorrow morning and asked them to specifically check the lambda sensor and surrounding area for carbon buildup. The fact that yours was fixed with a relatively straightforward repair gives me hope this won't be a major issue. I'll definitely ask about checking for water damage or contamination too, since the mileage is pretty low for sensor failure. I was worried it might be something much more serious with the exhaust system. I'll let you know what the scan reveals. Thanks again for all the helpful information, it's really given me a good starting point to discuss with my mechanic.