BMW X7 O2 Sensor Failure? Engine Light & Bad MPG Issues

Hey there! I had a similar issue with my 2019 BMW X5 last year. The symptoms you're describing sound very familiar, my X5 was showing the same signs, and I initially thought it was the O2 sensor too. Took it to my regular workshop, and it turned out to be a loose connection in the wiring harness going to the O2 sensor. The mechanic found that the plug connection had worked itself loose over time, causing weird readings. They fixed the connection and replaced a damaged cable section. Cost me 95 Euro, and the problem was completely solved, engine light went off, fuel economy went back to normal. Before I can give you more specific advice, could you share: What error code are you getting? Have you noticed any rough idling? When did these symptoms first appear? This'll help determine if you're dealing with the same issue I had on my X5.

Thanks for sharing your experience! My X7 has had these symptoms for about 2 weeks now. The error code I'm getting is P0141, and yes, there's definitely some rough idling, especially when the engine is cold. Last service was done at 139568 KM, and everything was fine until these issues started showing up. I'm hoping it's just a wiring issue like yours and not the sensor itself, will definitely get the connections checked first. Did your X5 also have a rough idle before the fix?

Hey again! Yeah, my X5 definitely had that rough idle too, especially during cold starts. When you mentioned the P0141 code, that's exactly what I got as well! It's interesting because while my issue turned out to be just a wiring problem, the symptoms were identical. Actually, I should mention something I forgot in my first reply, before getting it fixed, I tried cleaning the connections first (thought I could save some money, you know?). But in my case, that didn't solve it. The rough idle was really annoying, particularly in the mornings. My X5 would shake a bit for the first minute or so after starting up. With that mileage you mentioned, it could still be just connections like mine was, but I'd suggest getting it checked soon. These symptoms tend to get worse if left unchecked, my fuel consumption went up by about 20% before I got it fixed. Since you're experiencing the exact same error code and symptoms, I'd bet you're dealing with something similar. Just make sure whoever checks it takes a good look at the wiring harness first before replacing any parts. Could save you some serious cash! Let me know what you find out, I'm curious if it turns out to be the same issue as my X5 had.

Hey, thanks everyone for the replies! Just wanted to update you all, I took my X7 to the shop today and had them check it out. You were right about checking the wiring first! Turns out there was corrosion in the connector, and a few wires were loose. The mechanic cleaned up the connections, secured everything properly, and replaced a small section of damaged wiring. Total bill came to about €120, which is way better than what I was expecting to pay for a new O2 sensor. The engine light's now off, and I've already noticed the idle is much smoother. Going to monitor the fuel economy over the next few days, but it seems to be improving already. Really glad I asked here before jumping to conclusions about needing a new sensor. Thanks again for sharing your experience with your X5, saved me both time and money! Will definitely keep an eye on those connections during future services to prevent this from happening again.