The other night, my stepdaughter calls and says she cannot get into her 2000 300m. I get there and find that neither the key fob nor the actual key will open the doors. I even try the key on trunk with no luck. So I slim jim the door and it opens, and the alarm goes off. Use the key to start the car and that works. When she gets home, we grab the spare. That key fob works to open up the car, but that actual key will not work on the doors or trunk either, even though it will start the car. Now I don't use the car, so I don't know if the keys ever worked, and she doesn't remember ever trying the key on the doors. Anyone have any thoughts? Could the doors and trunk been rekeyed and we just never got that key when she bought it used, or is it yet another electrical gremlin?

 

sounds like fob needs new batteries . sounds like the key switch has been replaced that's the only good key you have . they tossed the other keys for the door and trunk . have to make sure you keep the fobs working . this happen to me years ago on a different car.

 

I got the batteries replaced in the problem key fob and that works now. As long as we have two working remotes, I am happy at this point.

 

Try a little WD-40 in the key holes. If you never use them, they get sticky.