Keyless start intermittent fail
 

Probably once a week, first thing in the morning, when attempting to start the e350, I have the key fob in my pocket and when i push the start button, the display reads "key not available". So I pull the start button out , instert the fob and it starts. After that no more problem using the fob in remote. New battery in fob. Any ideas??

happens once in a while to me as well.
idk why does it happen but dont bother me much

Happened frequently on our 2015 E350 4matic. Wife refused to drive the car. After dozens of attempts to fix, we decided to sell the car.

So you push the start button, a signal is sent by the car to see if the key fob is near, the fob responds, the car receives the message sent by the FOB, and starts the car. Any part of that transaction could fail. I have no idea how to determine which part of the transaction fails.

I had key recognition issues a few times when my key was in the same pocket as my iPhone. I don’t let that happen anymore and the recognition problem is completely gone.

SOLUTION to "key fob not found"
 

OK, so occasionally the dash says "key fob not found". The reason? I carry my fob in my pocket all day and sometimes it one of its buttons get pressed then the car can't "find" the fob. I found that simply pulling the fob out of my pocket and pressing the "unlock" button will allow the key to be recognized. :)