Concorde 2001 Check engine code P1684

[fidget13a]

looked up this code and it said "evap leak monitor small leak detected" I turned on car today nad the light came on. Did the key on off thing and I got this code and P0456. Htat is battery disconnected lst 50 starts. htat lalso did ot happend unless dealer diconnected it last week when they changed oil. ANy suggestions from the experts? I have along trip in the morning

Thanks

[windowpane]

I *think* some have had the evap leak from a loose gas tank cap or if the car is turned on/left on while filling up the tank I cannot be sure though.