BMW 8 Series O2 Sensor Issues & High Fuel Consumption

Hi there! I've got some experience with BMWs, having owned a 2017 BMW 6 Series (and previously a 4 Series). Had a really similar issue with my 6er, engine light, crazy fuel consumption, the whole deal. Turned out it was indeed a faulty connection in one of the O2 sensor cables. Got it fixed at my regular workshop, cost me about 95 Euro. They found that the cable connection was loose and had some corrosion, which was messing with the sensor readings. Pretty straightforward fix, honestly. Before jumping to conclusions though, could you share which engine variant you have and what specific error codes you're getting? That would help me tell if it's the same issue I dealt with. Hope this helps! Let me know if you need more details.

Thanks for sharing your experience! Mine's a bit newer at 104185 KM and had its last service 3 months ago. Just got the error codes checked, it's showing P0172 and P0175, which point to a rich fuel mixture. Really sounds similar to what you experienced with your 6er. Did your mechanic mention anything about checking the MAF sensor as well? Just wondering since I've read these issues can sometimes be related. The fuel consumption part is what's really bugging me, gone up by almost 30% in the last few weeks. Thanks for the heads up about the repair costs too. Good to have a ballpark figure in mind before heading to the shop.

Hey again! Yeah, those error codes, P0172 and P0175, they're exactly what I dealt with on my 6er. Funny you mention the MAF sensor because my mechanic actually did check that too during the diagnosis. In my case, it turned out to be just the O2 sensor issue, but it's smart to check both since they can give similar symptoms. I remember my fuel consumption shot up by about 25-30% too, super annoying when you're filling up way more often than usual. Honestly, the moment they fixed that loose connection on my O2 sensor, the fuel consumption went right back to normal. One thing I didn't mention before, my mechanic also cleaned the sensor while they were at it. Said it had quite a bit of carbon buildup, which probably didn't help matters. Since your car's got similar mileage to what mine had when this happened (mine was around 98000 km), might be worth asking them to clean it even if they just end up fixing the connection. Tell you what, keep me posted on what your mechanic finds. Really curious to know if it's the same exact issue. These BMWs can be pretty consistent with their quirks!

Thanks so much for all the detailed info! Really appreciate you taking the time to share your experience, especially about the sensor cleaning. I've actually just booked my car in for tomorrow morning, definitely going to mention both the O2 sensor connection and the cleaning to my mechanic. You're right about these BMWs and their quirks! It's honestly pretty reassuring to hear someone else had the exact same codes and symptoms. I was worried it might be something more serious (and expensive!). Will definitely get them to check both sensors while they're at it, rather be thorough than have to go back again. Thanks again for all your help! I'll try to remember to update this thread once I get it sorted, might help someone else with the same issue down the line. Really glad I asked here!