My 2011 GL 550 has intermittent issues recognizing the key to start. When I turn the key to position 3 frequently I do not get the lights in the dash recognizing that the car is ready to start, turning to position 4 at this point does nothing. At this point, sometimes I can take the key out, close the driver door and try again and it works. It does almost seem like opening and closing the driver door triggers this. But it is not always the cure.

Things I've tried:
Replaced batteries twice in both keys to to make sure they're as possible.
Tried the key fob combination to re-sync the key to the car. Seems to work for maybe 6 start but then back to it.
Car battery is fine.
Starter is new
Mechanic doesn't have an answer

Help! Please

 

Have you tried to clean the key hole?
I’m guessing that your key has an infrared sensor and, where it attaches has a receiver. Sometimes it gets dirty and doesn’t activate the system.