I have a 2016 S550 with 53,000 miles and the check engine indicator came on two months ago. It was a week after I paid for my B service from the dealer. They said two codes showing up and could only clear one at the service desk without taking it in for service. Also, I replaced the gas cap as they recommended. They said drive it for a few days and see if the light goes out. They assured me it was something minor. So, after a couple of weeks the light was still on. I ran into a Mercedes part guy and he said it sounds like it could be a line to the cannister or the cannister itself.

I have all of my warranty work done at the dealer and since my warranty just expired, I went to any shop. He filled the chamber with smoke and then cleared both of the codes. I picked the car up and the check engine light was off but by the time I got home it was on again. When I reached out to him he said I need to drive the car at least 5 times before the code will clear. Just curious has anyone else had this problem with the check engine light?
BeardSL

You need to get yourself a scanner and see why the light is coming on again:

 

Will do, thanks for the tip.