BMW M2 Rough Running and Failed Emissions, Need Help!

Had the same issues with my 2016 BMW M4. Lambda sensor went bad and caused similar symptoms, rough idle, sluggish acceleration, and that typical rich fuel smell from the exhaust. Check engine light was constantly on. Took it to a certified BMW shop because this isn't something you want a general mechanic to handle. They diagnosed failed oxygen sensors and had to replace both up and downstream sensors. The faulty sensors were causing incorrect fuel mixture readings. It's a serious issue that needs immediate attention since it affects engine performance and emissions. Running rich fuel mixture can damage your catalytic converter if left unfixed. My repair took about 4 hours total. The car ran perfectly after the fix, smooth idle, proper acceleration, and passed emissions with flying colors. Definitely recommend getting it checked at a BMW specialist. These symptoms are pretty typical for lambda sensor failure on these engines.

Hey there! Yeah, I had exactly the same problem with my M2 last year. The symptoms you and described match perfectly what I experienced. The specialist diagnosed faulty lambda sensors in my case too. Do you remember roughly how much you ended up paying for the whole repair? Just curious because prices seem to vary quite a bit. Also, has everything been running smoothly since the fix? Mine's been perfect after the repair, but I'd like to know if you've had any related issues pop up later.

Hey again! Happy to update you on my M2 situation. After seeing the BMW specialist I mentioned earlier, they fixed the Exhaust treatment malfunction completely. The total came to 375 € for replacing the faulty Lambda sensor, which was actually a bit less than I expected. Since the repair, my M4's been running like a dream, no more rough idle, acceleration is back to being properly responsive, and that annoying exhaust smell is completely gone. Best of all, no check engine lights or any other issues have popped up in the months since. Honestly, it feels just like when I first got the car. It was definitely worth getting it sorted at a proper BMW specialist rather than trying to save money with a general mechanic. These sensors are pretty sensitive bits of kit, and getting them properly diagnosed and replaced is crucial for keeping these engines running right. Glad to hear yours is running well too after the fix. These M engines are fantastic when everything's working as it should!

Thanks for sharing the follow-up! Just got back from getting my M2 fixed and wanted to update everyone. Had a pretty similar experience, took it to a specialist who found the faulty lambda sensors right away. They did a thorough inspection, replaced both sensors, and ran diagnostics to make sure everything was working properly. The whole thing cost me a bit more, around 450 for parts and labor, but totally worth it. The difference in performance is like night and day! Engine's running smooth again, got that crisp acceleration back, and no more funky exhaust smell. Just passed emissions too, which is a relief. Funny thing, while I was there, the mechanic showed me the old sensors and explained how they affect the fuel mixture. Really helped me understand why these little parts can cause such big problems. Definitely learned my lesson about getting these issues checked out quickly by the right people. Thanks again for all your help. Really glad I didn't try to cheap out on this one!