BMW 3 Series NOx Catalyst Issues, Power Loss & No Start

Hi there! I have some experience working on cars and actually dealt with something similar on my 2006 BMW 5 Series diesel last year. The symptoms you're describing sound very familiar. Mine had a leak in the exhaust system that was causing similar issues, engine light, power loss, and emissions problems. Took it to my regular workshop and they found cracks near the NOx catalyst. The whole repair including parts and labor ran me about 265 Euro. Before we dig deeper into what your specific issue might be, could you share: Current mileage on your car? Any unusual sounds or smells? Have you noticed any smoke from the exhaust? This info would help me give you more relevant advice based on my experience with my 5 series. These exhaust system issues can get tricky with diesels, but they're usually fixable without breaking the bank.

Hey, thanks for your detailed response! Currently at 161236 KM and had my last service about 2 months ago. No weird sounds really, but I do notice some white smoke occasionally when starting up cold. I'll definitely get it checked for exhaust leaks based on your experience. Did your car also have starting problems before you got it fixed? Just trying to figure out if I'm looking at the same issue or something else entirely.

Hey again! Yeah, my 5 Series definitely had similar starting issues before I got it fixed, especially on cold mornings. The white smoke you're describing is exactly what I experienced too. Mine would sometimes struggle to start and when it did, there'd be that white puff of smoke. After dealing with my car's problems, I'd bet we're looking at the same issue here. Just before I got mine fixed, it got so bad that I had a couple of mornings where it wouldn't start at all, super frustrating when you're trying to get to work! The workshop found that the leak near the NOx catalyst was actually causing more damage than I initially thought. It was messing with the sensors, which explained the starting problems and the check engine light. Once they replaced the catalyst and fixed the leak, all those issues cleared up. Just a heads up though, make sure you get it checked soon. I waited a bit too long and ended up having to replace more parts than I would've if I'd tackled it earlier. Learned that lesson the hard way! Let me know what your mechanic says when you get it looked at. Always curious to hear how these repairs turn out for others with similar BMWs.

Thanks for sharing your experience, this is really helpful! You've convinced me to get it checked out ASAP. The similar symptoms, especially the cold start issues and white smoke, make me think we're definitely dealing with the same problem. I'm going to call my mechanic tomorrow to schedule an appointment. Rather deal with it now than risk more expensive repairs down the line like you mentioned. I'll tell them to specifically check the NOx catalyst area and look for any exhaust leaks. Really hoping it's a straightforward fix like yours was. The car's been great otherwise, so it's worth getting this sorted properly. I'll update once I know more about what's going on with mine. Thanks again for taking the time to share your experience, it's given me a much better idea of what I might be dealing with!