I just went to use my message seats and noticed that the seats aren’t functioning. The active seats aren’t bolstering and I can’t get either seat to massage or fill any of the bladders. I hear the switching of the solenoids in the seats switching just not filling with any air. I checked the fuse #421 in the trunk but it’s good. Everything else in and on the car works perfectly. Could the pump in the trunk have gone out? I haven’t even used those functions until today. I actually was able to push out all the air in the drivers bladders including pushing out the side bolsters, ( no resistance). Has anyone had their pump just go out for no reason? Also, where is the pump located and is there a way to test it?

Did you try resetting the system

It was the pump. I just ordered a new one

Found this thread. Someone with similar experience. Good luck

https://mbworld.org/forums/s-class-w...cuum-pump.html