Greetings! I am looking to buy a used Subaru Outback 1998 that has the check engine light on w/ the message P0440 EVAP. In searching this group, I found that a possible solution can be that the gas cap just needs to be replaced as the seal may be leaking. In addition, it seems it can be a small leak anywhere in the system which could be a real pain in the ass and $$ to fix.
My simple question is, if it is the gas cap, will putting a new gas cap on cause the light to automatically turn off? Or, does it need to be reset by the dealer and then we wait to see if it comes back on?