Replace The Key Fob Battery on a 2005 Subaru Impreza
Replacing the batteries in any 2005-2006 Subaru key fob remote is just about as easy as it gets. The one pictured is for my WRX STI, but will apply to any Subaru fob from these same years. Follow these simple steps to get your remote door locks working again.
Near the end of the fob, there's a little indentation. Use a flat screw driver or key to pry the 2 halves of the plastic clamshell apart.
Once it's apart, you can easily see the battery. Pop it out without bending any of the springy metal contacts.
The PCB of the fob recommends you to not touch the terminals. I suppose the oils on your fingers could contribute to corrosion.
Place the new battery in the fob. The flatter, positive side (+) goes down - toward the black plastic.
Snap the 2 halves together and call this job done!