I have a 08 S80 with a keyless remote issue. If its a short time from from when I lock and unlock the vehicle, there are no problems. However if it's been an extended amount of time between unlocking and locking vehicle the keyless remote fails and I have to open the car with valet key (which activates alarm). I welcome any feedback.

 

You should be still under warrenty.

 

have you changed the battery in the fob?
My 07 s80 did same , fresh battery should work

 

Changed the battery in both remotes and still no dice.