BMW M3 Rough Running and Limp Mode Mystery

Hey there! I actually dealt with something very similar on my 2019 BMW M4. Had the same symptoms, rough running, jerking, check engine light, and emissions issues. Turned out I had a significant exhaust leak where the manifold meets the catalytic converter. The manifold gasket had completely deteriorated and was causing all sorts of problems. When I finally took it to a garage, they found multiple cracks in the manifold itself. It was a pretty serious issue that needed immediate attention, as it was affecting engine performance and could've led to more damage. The repair involved replacing the exhaust manifold, gaskets, and a few sensors that had been damaged by the excessive heat. It wasn't a quick fix, took them nearly two days to complete everything properly. If your symptoms match mine, I'd strongly suggest getting it checked soon. These issues typically don't resolve themselves and can cause more extensive damage if left unchecked. The M-series engines are tough, but they need proper maintenance when things go wrong. Hope this helps with your decision.

Hey, thanks so much for sharing your experience! That sounds exactly like what I'm dealing with my M3 right now. Do you remember roughly how much you ended up paying for the whole repair job? Also, has everything been running smoothly since the fix, or have you noticed any other issues pop up? Just trying to get an idea of what I might be in for. Thanks!

Hey again! Glad to give you an update! After getting my M4 fixed, it's been running like a dream, no more uneven idle or jerking around. The repair sorted out all those annoying symptoms completely. Cost me 265 € to fix the exhaust leak, which honestly wasn't as bad as I was expecting given how much trouble it was causing. I know you were worried about picking a mechanic, but I'd definitely say it's worth getting it checked out. Since the repair, my car's been performing perfectly, no check engine lights, no limp mode, nothing. It's back to being the smooth beast it should be! It's such a relief not having to worry about those issues anymore. Trust me, once you get it sorted, you'll wonder why you waited. These M engines are fantastic when everything's running right. Let me know how you get on with yours!

Thanks for the follow-up! Actually, I bit the bullet and took my M3 to a new mechanic yesterday. You were spot on, it was an exhaust manifold issue, along with some worn-out sensors. Cost a bit more than yours at about 400, but honestly, it was worth every penny. The mechanic was fantastic, showed me exactly what was wrong and explained everything. Car's running beautifully now, like a completely different machine. No more jerking, no check engine light, and the acceleration is smooth as butter again. What a relief! Really appreciate you sharing your experience, it gave me the push I needed to get it sorted before it turned into something worse. These M cars sure are something special when they're running right! Guess sometimes you just need to trust a new mechanic and get things fixed properly. Thanks again for all your help!