Please refer to this video: https://www.youtube.com/watch?v=BPuw6GrWX9Y&ab_channel=1AAuto%3ARepairTips%26SecretsOnlyMechanicsKnow
You can jump to 6:34 to this issue directly.
My 2014 E350 has this issue. According to this video, it is a common issue for W212 E350. I am wondering if any of you have this issue? Has any one did DIY fix of this issue? Thanks.