BMW NOx Sensor Issue: Expert Help and Cost Advice Needed

Hey there! I had a similar issue with my 2019 BMW M5 last year. The check engine light came on with emission-related codes. Initially thought it was just the NOx sensor like you, but it turned out there was a loose connection in the wiring harness connected to the sensor. The mechanic found that some connectors had corroded slightly, causing intermittent signal issues. The fix involved cleaning the connections and replacing a few damaged pins in the harness connector. While not a severe problem, it's important to address it promptly as faulty readings can affect engine performance and emissions control. My case wasn't too serious, but left unattended, these issues can potentially damage other components in the emissions system. The repair involved about half a day at the shop. Just make sure whoever works on it has experience with BMW's emission systems, they can be quite specific. Hope this helps with your decision!

Thanks for sharing your experience! That's really helpful as it sounds exactly like what I'm dealing with. Would you mind telling me how much you ended up paying for the repair? Also curious if you've had any other emission-related issues pop up since they fixed it? I'd like to get a sense of whether this might be a one-time fix or if I should expect more trouble down the road.

Hey again! Glad to give you an update! Since my last post, I actually took my M5 to the mechanic and got everything sorted. You'll be happy to know it was exactly what I suspected, just a faulty connection to the NOx sensor. The total bill came to 95 € for fixing the cable and plug connection, which was honestly a relief considering how expensive BMW repairs can get! Since getting it fixed, I haven't had a single emission-related problem pop up. The check engine light hasn't come back on, and the car's running smooth as butter. It's been about 8 months now, and everything's still perfect. Looking back, I was probably worrying too much about it potentially being something bigger. My advice would be to get it checked out sooner rather than later. These kinds of issues usually turn out to be pretty straightforward fixes when you catch them early. Just make sure you're going to someone who knows their BMWs, makes all the difference! Let me know how it goes with yours! Always happy to share more details about my experience if you need them.

Thanks so much for all the detailed info! I actually just got back from the mechanic today, and you won't believe it, it was almost the same situation as yours. The mechanic found some corroded wiring connections near the sensor. They cleaned everything up, replaced a couple of damaged connectors, and the check engine light is finally off! The whole thing cost me around 120, which feels like a bargain considering how worried I was about potentially needing to replace the entire sensor. They had it fixed in about three hours, and the car's running great now. The mechanic also checked the rest of the emission system just to be safe, and everything else looked good. Really appreciate you sharing your experience, it definitely helped me feel more confident about getting it checked out instead of putting it off. I'll keep an eye on things, but hopefully, this will be the end of my emission system troubles for a while! Thanks again for all your help!