Hello I would have a problem now too I have a 2004.09 SL 500 with Keyless go in the key I have 2 keys one has always started with Keyless the other has only revealed the access in car and when I then press the start button at the switch button which always only jumped between position 1 and position 2 ….. So I always used the working key there also the start process worked today at noon but my wife took the replacement key and with Him over the Ignition lock started… since that also the other key no longer works.. So the car opens with both as it should be only when I then press the button he jumps back and forth again only between ignition settings 1 and 2 can it be that the knob has lost its programming? or is that more due to the keys I just don’t know how I could proceed and would be grateful for tips