BMW Check Engine Light + High Fuel Use: O2 Sensor Issue?

Hey! I have some experience working on BMWs. I actually faced a similar issue with my 2019 BMW 3 Series (also had a 4 Series back then). The symptoms were exactly like yours, check engine light, higher fuel consumption, and emissions problems. Took it to my trusted workshop, and it turned out to be a loose connection in the oxygen sensor wiring harness. The mechanic found that the plug wasn't properly seated, which caused intermittent connection issues. The fix was pretty straightforward, they cleaned the connector, reseated it properly, and secured it. Total cost was around 95 Euro, mostly labor. Before I can give more specific advice, could you share: Which engine variant you have? What's the exact error code showing up? Have you noticed any rough idling or hesitation while accelerating? This would help me understand if you're dealing with the same issue I had.

Thanks for sharing your experience! My mileage is currently at 92201 KM and I just got the error code checked, it's showing P0141. Regarding your questions, I have the 2.0L gas engine, and yes, I've noticed some slight hesitation during acceleration, especially when the engine is cold. The idle seems mostly normal though. I really appreciate the detailed info about your repair. That's actually reassuring to hear it might just be a connection issue rather than a complete sensor failure. Did you notice any improvement in your fuel economy right after the fix? I'm currently burning through fuel like crazy and hoping for a similar quick fix.

Hey again! Thanks for providing those details. Yes, I remember when I had this issue with my BMW, the P0141 code is exactly what I got too! And with the same 2.0L engine, what a coincidence. The symptoms you're describing are spot on with what I experienced. That hesitation during cold acceleration was super annoying, right? In my case, while the loose connection was part of the problem, they actually ended up finding that the O2 sensor heater element itself was failing. Unlike my initial repair, I had to get the whole sensor replaced. After the sensor replacement, the fuel economy improved dramatically, went back to normal within like two tanks of fuel. The hesitation disappeared completely too. Just to give you a heads up, the repair cost was more than my first fix, around 300 Euro including parts and labor. Quick tip though, before they replace anything, ask them to check the wiring and connections first. Sometimes carbon buildup around the sensor can cause similar issues too. They might be able to clean it and save you some money. By the way, have you noticed any black smoke from the exhaust? That was another symptom I forgot to mention earlier that I experienced with mine.

Thanks so much for all the detailed info! No black smoke from the exhaust in my case, which is probably a good sign. I'll definitely have them check the wiring and connections first before jumping straight to replacing the sensor, that's a really good tip! The similar symptoms and especially the same error code make me feel more confident about what I'm dealing with. I'm actually heading to the mechanic tomorrow, and I'll make sure to mention everything you've shared. Really hoping it's just a connection issue like your first fix, but at least I know what to expect if it ends up needing a full sensor replacement. 300 Euro for the sensor replacement isn't as bad as I was fearing, I was worried it might be something much more serious. Fingers crossed the fuel economy bounces back quickly like yours did. Thanks again for taking the time to share your experience, it's been super helpful!