I recently purchased a 2012 E550 Cabrio. Prior to purchasing I checked the vin and noted all the options, keyless go was one of them . When I went to see the vehicle it did not have the button in the dash but the door locks operated properly without using the key fob button and the car started with the key . Since then I called my local dealership and he sold me the appropriate button after confirming that the car had keyless go . I plugged the button into the key slot as described in the manual and when I pushed the button to start the car it read "key not detected". If I push it several times it says remove button and use key. Can anyone shed some light on what is going on. I am bringing the car in for another reason in 2 weeks but I would like to figure this out beforehand.

 

Sometimes mine won't recognize the presence of the key FOB unless I hit one of buttons. Try hitting the unlock button and I'm guessing the car will then recognize it and the pushbutton start will work.

 

I recently purchased a GL450 with Keyless Go. During the test drive we used the key in the lock. Upon returning to the dealer, I asked wassup? Salesman said the buttons had a habit of walking away. He took one out of his desk and inserted it in the lock. Push button worked right away. However, my wife's ML350 kept telling me "key not detected". Like yours, the touch door unlock worked. Changed out the cheap-a$$ Chinese 2025 battery with a name brand and the problem went away.

 

Just changed batteries in both keys and it started . Thanks !

 

Best make sure you get a Faraday pouch to keep the fob in now so the car doesn't get taken by the local low life.

 

That's something I did not consider . Thanks for the heads up.

 

There's a trick to getting the button to sync with the key if the notice, "Key Not Detected" comes on.

Turn ignition on with button, then press the unlock button on the key. This helps sync the key with the button.

Then you should be able to start the engine using the button.