W214 Volume Decreases Automatically EQUIPPED with Burmester 4D
Regarding the dealership and the mechanics working on it. They are just guessing much of the time when it comes to the whole MBUX system. If there is a code then it's more straightforward, but these type of issues are much more trial and error which is what you are experiencing. I can't say that I've heard of others having the issue you described but you may be in the 0.01% of W214 owners in how you listen to music. Like you, I like loud music but not max in this car and the EQ I keep at flat (0) and instead use the sound personalization to tune the sound. Then I listen to music from a USB drive and have been growing a collection of Dolby Atmos music that sounds amazing in this car. I had an issue that has been going on for over a year that I posted about here. I brought it in 3 times to get this fixed and one time they had it for nearly 2 weeks and still no solution. The engineering team in Germany have been working on a solution for over 2 months and believe they finally have a software fix. I bring the car next week for the update. I bring this up only to point out that if it's a software issue, it vlcan take a while to fix and if you are experiencing a rare issue like you (and me) are, it will be challenging for them to figure out the root cause.
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its highly unlikely that you bought the car on 9th May 2026
That said, yes the 4D is the bass resonators in the two front seats. They don't produce sound in the traditional sense but they will cause physical vibrations in your back.
My advice is wait for the dealership to diagnose and fix which could take a while as these systems are much more complex than the sound systems of yesteryear. Then when you do get it back, take it easy on the volume and bass. I'm guessing you are young which is no dig, we were all young at some point. When I was younger I listened to very loud music all the time and now that I am bit older I wish I hadn't. I still listen to it loud every now and then. Sometimes too loud, but I keep it at a comfortable volume most of the time. Still can't help myself when one of my many favorite songs come on.
Good luck and hope they get it fixed asap.
What you might be encountering is an issue with Windows (audio devices with option of allowing applications to control the volume), try and disable any setting related to Audio Normalization, and see if that does the trick.











