First of all, new to the forum. Second, I drive a 2002 C240. Now the problem. I've had the car for about 3 weeks (bought from a dealership) and it seems that the battery in the key has been goin erratic and I think that just putting in a new one will solve the problem. The question is, how do I get to the battery? Thanks for any help.

 

Go back to the dealer and ask them. You must have some kind of warrenty, 30 days or more. Oh welcome on board and enjoy your ride.

 

To change the batteries, take out the metal door keep and on top of the electronic key there is a small button which is hidden the the metal door lock key, take the tip of the key and push the button in while lifting, not hard as gently is the operative word here. the battery holder will slide out there are two batteries you can buy at radio shack, there lithium, the same stuff crazies injest to become de crazed. installation is making sure the battery have the correct polarity, check them as you slide out the holder as to how they are placed, I thing is it positive up on both, but no sure as I haven't changed one them in over a year, then just snapping back the holder, gently, as you have to be careful not to bend the prongs that hold the batteries in place. But first go to the dealer, it has to be under warranty and if it is the batteries they should replace them for free. But use all the functions before you leave to make sure it is a battery problem and not the key itself. They are cheap, but again they are covered even under new car warranty.

 

Thakns for the help
I'm pretty sure its onthe key itself because the buttons have been working on and off, but with no regular consistency for the past few days. I'll try to track down some batteries 2morrow.