BMW 4 Series Exhaust Flap Failure: Fix and Cost Guide

Hey there! I had a similar issue with my 2019 BMW M340i last winter. The exhaust flap actuator was failing, causing the valves to stay in an open position. Like yours, mine got super loud on cold starts, and the exhaust note was uncontrollable. Took it to the garage where they found water damage on the actuator motor and some corrosion on the connecting cables. It wasn't a critical safety issue, but leaving it unfixed would've eventually caused the flap to get stuck permanently. The mechanic also mentioned potential damage to other exhaust components if left unchecked. The repair involved replacing the actuator motor and the wiring harness. Had to wait a couple of days for parts, but the actual work took about 3 hours. This is definitely something you want a proper BMW specialist to handle, as they'll need to program the new actuator to work with your car's electronics. Based on your symptoms, sounds very similar to what I experienced. Get it checked soon to avoid any potential damage to other components.

Thanks for sharing your experience! That sounds exactly like what I'm dealing with. Mine's been doing the same thing with that loud cold start and stuck flaps. Quick question, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been working fine since then, or have you noticed any other issues pop up? Just trying to get an idea of what I might be looking at cost-wise and if I should expect any other problems down the road.

Hey again! Just wanted to follow up on your questions. Yes, I can definitely tell you about the costs, I paid 190 € for the entire repair, which covered both parts and labor. And I've got great news to share, since getting it fixed, the exhaust flaps have been working perfectly! No more embarrassingly loud cold starts or stuck flaps to deal with. The repair was totally worth every penny in my opinion. My M340i is back to running exactly how it should, and I can finally control the exhaust note again. It's been about six months since the fix, and I haven't had a single issue pop up related to the exhaust system. The mechanic did a really solid job. If your symptoms are matching what I experienced (and it really sounds like they are), you're probably looking at a similar repair cost. Just make sure you get it sorted soon, like I mentioned before, leaving it unfixed could lead to more expensive problems down the line. Let me know if you need any other info! Happy to help a fellow BMW owner out.

Thanks a lot for all the details! Just got back from the mechanic today actually. You were spot on, it was the actuator motor, just like in your case. My bill came to a bit more since they found some additional wiring that needed fixing, but honestly, I'm just glad it's sorted now. The whole experience was way better than I expected. The mechanic walked me through everything they were doing, showed me the old corroded parts, and even let me hear the difference before and after the fix. No more thunderous cold starts waking up the neighbors! The car's running beautifully now, the exhaust note is back to normal, and I can finally use those flaps again. Really appreciate you sharing your experience, it helped me know exactly what to expect and gave me confidence in dealing with the repair. Sometimes it's just good to hear from someone who's been through the same thing. Time to enjoy my properly functioning BMW again! Thanks for all your help!