M2 Owner Battles Multiple Engine Issues And Failed Starts

Hi there! I had a somewhat similar issue with my 2017 M4 (coming from some experience with BMWs). The symptoms you're describing sound very familiar, my car had exactly these problems last summer. Got it checked at my regular workshop and it turned out to be a nasty exhaust leak near the manifold. The repair, including parts and labor, cost me 265 Euro. What a relief it wasn't the NOx catalyst! The mechanic actually showed me where the leak was, and it was causing all sorts of sensor readings to go crazy. Before I can give you more specific advice, could you tell me if you're hearing any unusual noises, especially when accelerating? Also, where exactly is the exhaust leak located (if you know)? The M2/M4 exhaust systems are pretty similar, so I might be able to help more with those details.

Had my last service just 2 weeks ago at 98692 KM and the mechanic checked everything thoroughly. Based on your description and my experience, it does sound like an exhaust leak, but mine was closer to the turbo connection point. Started with similar symptoms, engine light, power issues, and rough starts. My repair was a bit pricier though, around 900 for parts and labor because they had to replace some surrounding components that got damaged from the leak. The NOx catalyst was actually fine, turns out these leaks can trigger similar error codes. I'd suggest getting it pressure tested first before jumping to more expensive repairs. Let me know if you need any specific details about what they did to fix mine.

Hey again! Thanks for sharing those details about your repair. You're absolutely right about the turbo connection point, that's actually a common trouble spot on these M engines. After reading about your experience, I'm pretty sure I oversimplified my initial response about my M4's repair. Looking back, my case was actually more complex than I first described. While my initial repair was indeed around 265 Euro, that was just for diagnosing and fixing what we thought was a simple leak. But just two weeks later, the same symptoms came back, and that's when we discovered the leak had actually damaged the connection points near the turbo, similar to your situation. The full repair ended up being closer to 850 Euro. Did your mechanic mention anything about the gaskets around the turbo area? In my case, they had deteriorated pretty badly, which contributed to the whole issue. I've learned that these leaks can be really sneaky, they start small but can cause a cascade of problems if not caught early. After my experience, I've become much more attentive to any changes in engine sound or performance. These M engines are fantastic but they definitely need proper care when these issues pop up.

Thanks for the follow-up! Yes, actually, the gaskets were a big part of my problem too, I should've mentioned that earlier. My mechanic said the original gaskets had completely deteriorated, which is what led to that nasty leak at the turbo connection. He showed me the old ones and they were basically crumbling. What's really interesting is how similar our experiences were with the repair costs escalating after finding more damage. You're spot on about these issues being sneaky, what seems like a simple leak can really snowball. My mechanic actually recommended replacing all the gaskets in that area as preventive maintenance, even the ones that looked okay, just to avoid future problems. Since the repair, my M2's been running like new again, no more power loss or starting issues. I've started paying way more attention to how the car sounds and feels too. These M engines are incredible machines, but they definitely let you know when something's not right. I'm just glad it wasn't the NOx catalyst like I initially feared. Thanks for sharing your experience, it's really helpful to hear from someone who's been through the same thing.