BMW 2 Series NOx Sensor Woes: Fix & Cost Help Needed

Had the same problem with my 2018 BMW 3 Series diesel last month. The NOx sensor was indeed faulty and caused similar symptoms, check engine light, emissions problems, the works. When I got it checked, turned out the wiring harness connecting to the NOx sensor was corroded, and the sensor itself was toast. Not just the sensor, but the whole assembly needed replacement. It was a serious repair since bad NOx readings can damage your catalytic converter if left unfixed. My mechanic showed me where the corrosion had spread into the connector housing. They had to replace both sensors (upstream and downstream), plus the wiring harness. The whole job took about 4 hours. Since the fix, the car's been running perfectly, no check engine light, passing emissions with flying colors. If you're seeing similar symptoms, don't wait too long. The longer you drive with a faulty NOx sensor, the more risk you run of damaging other components in your emissions system.

Thanks for sharing your experience! That's exactly what I was worried about, the whole sensor assembly being affected. Good to know I'm not the only one who's dealt with this headache. Just curious, do you remember roughly how much you ended up paying for the complete fix? Also, has everything stayed sorted since the repair, or have you noticed any other issues popping up? Would love to know what to expect cost-wise and if I should be watching out for anything else.

Hey there! Just wanted to follow up about my BMW NOx sensor repair. Since my last post, I actually got it sorted properly, turns out it wasn't nearly as bad as my initial experience. The mechanic found it was just a dodgy cable connection to the sensor that needed fixing, not the whole assembly like I originally thought! Total bill came to 95 € which was a massive relief compared to what I was expecting. The check engine light's been off since the repair, and the emissions are spot on now. No other issues have cropped up either, she's running like a dream. Really glad I got it checked when I did. Seems these NOx sensors can be tricky, sometimes it's a major job like I first thought, but other times it's just a simple fix like mine turned out to be. Definitely worth getting it properly diagnosed rather than assuming the worst. Hope this helps with your decision making!

What a relief to hear your repair was just a minor fix! I actually took your advice and got my car checked yesterday. The mechanic I found was fantastic, really knew his stuff with BMWs. He did a thorough diagnosis and found out my issue was pretty similar to yours. Turned out I just needed a sensor cleaning and recalibration. The whole thing only took about an hour and cost way less than I expected. The mechanic showed me the problem, there was just some buildup affecting the sensor readings. He also checked the wiring connections while he was at it, just to be safe. The car's running perfectly now, no more check engine light and the exhaust issues are gone. Really glad I asked here first instead of going back to my old mechanic who probably would've charged me for unnecessary repairs. Thanks again for sharing your experience, it really helped me make the right choice!