Subaru Problems? Ask a Mechanic for Answers ASAP
Do you know what the code was that was stored the first time it was checked at the service station?
Most likely it was an evap leak, which deals with emissions. Should be safe to drive either way, you could disconnect the negative and positive battery cables, hold them together for a few minutes and reconnect to battery, that would also reset the system.
Hard for me to help you diagnose without the codes. You will need to wait until the lights come back on and then bring to the dealer.