Join Date: Jun 2006
Location: Eastern ON Canada
Car: 07 OBW 2.5i D-4AT
Feedback Score: 5 reviews
And, you really want to have the dealer load up the keyless entry module with both the new and remaining key/fob codes, thereby eliminating/erasing the system's record of the one that was lost.
Otherwise, the lost one could still be used to open/drive the car. If the key was lost near to home, it might be all too easy for someone finding the fob to identify which car it belongs to by pressing the panic or lock/unlock button when near a 08+ Subaru. (The fob and key are together, unlike earlier -- my 07 -- where the fob is separate. Combined key/fob is "driveaway".)
The keyless module can register, I believe, up to four fobs. Two are already in, and there's two spare places. By loading in the two remaining fobs (your original and a new one) twice each, all four places are taken up, and the lost fob's registration is erased (replaced). That way, the lost fob would not be recognized.
(I would add that if was lost nearby, perhaps someone finding it could go around seeing which car responds to the fob and then leave a note for the driver with info as to where the fob can be retrieved. There's still hope . . . )