I'm looking for some help please. I have the above car and recently had the battery changed as it was flat. Since then, maybe coincidentally, the fob has stopped working in the ignition. I only have 1 fob as my son lost the other one. The fob battery is good and it opens and closes the car but won't activate the ignition. I've been quoted up to $1700 for a new fob but I want to be sure what the problem actually is. I'm pretty handy but ageing. Can anybody assist with fault finding so I can be sure what requires attention whether it's the fob, fuse or ECU? Thanks Mick

 

Hello

I had the very same issue on a 05 CLK 320. The circuit board on the key fob was bad. I ordered a new fob from the dealer - fixed.

Take your old fob and press one of the lock or unlock buttons. If you see the red LED light come on as you do so, then the key fob is probably okay. If not, it is bad.