BMW X4 O2 Sensor Issues: CEL & High Fuel Consumption

Hey there! I have some experience working on BMWs and had a similar issue with my 2017 BMW X3 last year. The symptoms you're describing sound exactly like what I went through! In my case, it turned out to be a loose connection on the oxygen sensor wiring harness. My mechanic diagnosed it, fixed the connection, and cleared the codes. The whole thing cost me around 95 Euro, and my fuel consumption went back to normal right away. Such a relief! Before I share more specific details though, could you tell me which engine variant your X4 has and what error codes you're getting? Also, have you noticed any rough idling or hesitation during acceleration? This info would help me give you more targeted advice based on my experience. BTW, the X3 and X4 share a lot of components, so these issues often pop up in both models.

Thanks for the detailed response! Last service was just 2 weeks ago, and I'm at 190381 KM. Mine is showing the P0141 code specifically. I'm definitely experiencing the hesitation during acceleration, especially when the engine is cold. The fuel consumption has gone up by about 20% in the last month. Considering just replacing the oxygen sensor since it seems to be a common issue, but wanted to check if anyone else had success with just cleaning the connections first. The idle is actually pretty smooth though, which is making me second-guess if it's really the O2 sensor.

Hey again! Thanks for sharing those details. Yeah, I definitely know what you're talking about with that hesitation. When I had my X3's issues, I initially tried cleaning the connections like you're considering, used some electrical contact cleaner and checked all the wiring. Honestly, it helped for maybe a week, but then all the symptoms came right back. With that P0141 code and the cold-start hesitation you're describing, it really does sound like the O2 sensor heater circuit. My experience has taught me that once these sensors start acting up, especially at that kind of mileage (mine was around 180000 KM when it failed), cleaning is usually just a temporary fix. I ended up biting the bullet and replacing the sensor completely. Best decision I could've made, fuel consumption dropped back to normal, and that annoying hesitation disappeared completely. If you're experiencing the same symptoms I did, and especially with that specific code, I'd skip the cleaning attempt and just go for the replacement. Just make sure you get an OEM sensor or at least a high-quality aftermarket one. I made the mistake of trying a cheap one first, and guess what? Had to replace it again three months later. Learned that lesson the hard way!

Thanks so much for sharing your experience! I really appreciate you being honest about the cleaning attempt not being worth it in the long run. You've convinced me, I'll skip straight to replacing the sensor instead of wasting time with temporary fixes. That's super helpful to know about avoiding the cheaper sensors too, definitely don't want to do this job twice! I'll order an OEM sensor today and get it replaced this week. Your situation sounds exactly like mine, so I'm feeling much more confident about this being the right solution now. Really glad I asked here before spending time trying to clean everything. Thanks again for all the detailed advice, this is exactly the kind of real-world experience I was hoping to hear about! Will let everyone know how it goes after the replacement. Fingers crossed I'll have the same positive results you did with the fuel consumption and performance. Seriously appreciate you taking the time to help out with this!