BMW M3 Exhaust Flap Problems, Fixes and Parts Guide

Hi there! I have some experience working on cars and dealt with a similar issue on my 2012 BMW M4. The symptoms you're describing sound exactly like what I encountered. For me, the actuator that controls the exhaust flaps had failed. My mechanic diagnosed it using diagnostic software and replaced both the actuator and the flap valve. The whole thing cost me around 190 Euro, but it fixed the problem completely. The repair took about 2 hours. Before heading to the workshop, I tried troubleshooting with the control module, but the flaps wouldn't respond at all, sounds similar to your case. What's your current mileage and have you noticed any warning lights? Also, does the noise change when you switch between driving modes? This info would help me share more relevant details from my experience.

Yes, I've got the exact same symptoms! My M3 is at 176988 KM and just had its service last month. The exhaust note is way too loud in comfort mode, and it's super annoying during cold starts. I tried resetting the control module but no luck at all. Thanks for sharing the repair details, that's actually not as expensive as I feared. Did you notice any difference in performance or fuel consumption while the flaps were faulty? I'm planning to book it in next week, so it's good to know what to expect with the repair time.

Hey again! Yeah, I remember when my M4 had these issues, glad I could help with the initial info! About your question on performance and fuel consumption, I definitely noticed some changes while the flaps were acting up. My fuel consumption went up by about 1-1.5 liters per 100km, especially during city driving. Performance-wise, it wasn't drastically affected, but I could feel the car wasn't running as smoothly as usual, particularly during cold starts. Based on what you're describing and your mileage, it sounds exactly like what I dealt with. Since you've recently had a service, the issue is most likely isolated to the flaps/actuator system rather than something more complex. Mine started acting up around the 165000 km mark, so the timing fits too. Just a heads up, after the repair, it took a few driving cycles for everything to settle back to normal. The ECU needed to readjust to the new parts. Make sure your mechanic does a proper reset and adaptation after installing the new components. When mine was fixed, it was like having a new car again, proper exhaust note control and smooth cold starts. Let me know how it goes after the repair!

Thanks so much for all this detailed feedback! Really helpful to know about the fuel consumption impact, I've actually noticed the same thing but wasn't sure if it was related. Good to hear it's not likely to be anything more serious than the flaps and actuator, especially since everything else was checked during the recent service. I appreciate the tip about the ECU adjustment period, I'll make sure to mention this to my mechanic when I take it in. It'll be great to have proper control over the exhaust note again and get rid of those annoying cold start issues. Definitely feeling more confident about getting this fixed now, knowing it worked out well for you. Will let you know how everything goes after the repair next week!