code P0440 P0446 Evap emmisions control???

Check engine light came on.....checked it...brought up codes P0440 Evap emissions control system malfunction...and P0446 Evap emmisions control system vent circuit malfunction. Naturally...I replace the gas cap....which had a worn seal...reset the comp....then 2 days later...check engine light comes back on....and same 2 codes come up. Any suggestions on what else it could be?

Depending on what year the veh is it may be the fuel filler tube.