The diagram of the fuse box in the owners manual should give you at least an idea what fuse this is. It is probably labeled accessory. I would pull that fuse and replace it. Blown fuses do not always look blown. If that is not the problem, or even if it is, taking it to the dealer is a good idea. It is under warranty, why mess with it yourself? I've used an air compressor that draws over 10amps off my lighter socket so the fuse should not have blown if you only operate a GPS. The dealer should look into why it blew - if that is the issue.