BMW X1 NOx Sensor Issues, Emissions Test Failures Solved

Hey there! I have some experience working on BMWs, I drive a 2014 BMW X3 and previously owned a 320i. I actually faced a similar issue last month. My engine light came on and I had emission-related problems. After taking it to my regular workshop, they found it was just a faulty cable connection to the NOx sensor. The total repair came to 95 Euro, mostly labor costs since they had to carefully trace and fix the connection. Before jumping to replacing the whole sensor, you might want to have them check the wiring and connections first. It's often a simpler fix than expected. Could you share more details about: When did this start happening? Any other symptoms besides the check engine light? Are you getting specific error codes? This would help me give you more targeted advice based on my experience.

Thanks for sharing your experience! Mine's at 137686 KM and had its last service about 3 months ago. Actually, it started happening quite suddenly, the engine light just popped up while driving on the highway last week. Getting error code P0420, and the engine feels a bit rough when idling. The workshop quoted me around 800 for a new NOx sensor, which seems steep. I'll definitely have them check the wiring first based on your suggestion. Really hoping it's just a connection issue like yours was!

Hey again! Thanks for those details about your X1. That P0420 code is definitely familiar, mine showed the same thing before we found the wiring issue. Though I've got to say, based on what you're describing with the rough idle, your situation might be a bit different from what I dealt with on my X3. When mine started acting up, it was just the light, no rough idle or anything. The fact that yours is running rough makes me think we might be looking at something more than just a wonky connection. Don't get me wrong, still worth checking the wiring first, but you might want to have them look at the catalytic converter too. And wow, 800 for just a sensor replacement? That's way steeper than what I paid, even considering different workshop rates. Before you drop that kind of money, maybe get a second opinion? My regular guy always tells me there's often a cheaper fix if you diagnose things properly. Quick question, have you noticed any drop in fuel efficiency since this started? That might give us another clue about what's really going on here. When my X3 had issues, fuel consumption stayed pretty much the same, which is partly how we figured it was just a connection problem.

Thanks for the detailed follow-up! You've got me thinking now, I actually haven't checked the fuel efficiency since this started, but come to think of it, I did have to fill up earlier than usual this week. I've called another workshop that specializes in German cars, and they're willing to take a look tomorrow. They mentioned they'll do a full diagnostic check including the catalytic converter, which makes sense given what you're saying about the rough idle. Since my car's approaching 140000 KM, I guess I should be prepared for it to be more than just a wiring issue, but fingers crossed it won't be as expensive as that first quote! Really appreciate you taking the time to share your experience, it's definitely helped me ask the right questions at the workshop. I'll let you know what they find out, might help other X1 owners who run into similar issues down the line!