I have a 2008 E320 that I am having problems with the key fob unlocking the car. It will occasionally unlock the car after one push of the button, but sometimes it takes multiple pushes of the button. I changed the battery to no avail. It locks the car and unlocks the trunk fine. Also, a second key fob unlocks the car with one push of the button every time. Apparently the unlock switch in the FOB is faulty. Is it possible to clean this switch or am I out a lot of money replacing the key FOB?

 

The carbon contacts in the fobs are susceptible to getting dirty. Disassemble, clean up the PC board and the carbon contact with a fresh pencil eraser, and put it back together.