Ok so began getting this code dug a bit into it and did some testing, here’s a little info on what I did and found hopefully it helps
I was also having a hard time putting gas in had to pump slowly

so you have a vent line comes off where you fill the gas and plugs into the charcoal canister middle port
top of your canister is a purge line that goes into engine bay and is plugged into the famous purge valve Hyundai style lol
bottom port of charcoal canister goes into the vapour leak detection pump and out of the pump into engine bay into a filter housing on passenger side , I think it’s called the charcoal canister vent line
key here is this vapour leak detection pump is normally open , so air is venting always

ok so from my understanding when the system does it’s check it closes this vapour leak detection pump opens the purge valve and system goes into vaccum.
Now if your gas cap is loose or leaking the system will never purge and I think this is when you get that code.

What i did first was make sure my vent line was clear. I have a nitrogen tank with a 1/4 inch copper tube which happens to be a good tight fit on the vent line , the vent line is the middle port on the charcoal canister, when you apply pressure you can hear the air escaping via the gas cap and if it over pressurized the gas cap will relieve the pressure, I also exposed my fuel pump just to check things out. ( very dirty in there ) nice clean up
ok so blew air through vent line with and with gas cap on
next I blew air through charcoal canister vent line that goes into engine bay vent filter
now next I took out the top and middle port on the canister and blew air into the middle port and air should come out of top port of charcoal canister, if it doesn’t your canister is plugged and therefore your vent will not vent and you can’t pump gas fast , mine was clear
I think my problem is the gas cap as I replaced it and blew air into vent line into tank and didn’t notice as much air escaping , only when it got over pressured
so as you can see some of you replace gas cap and still have this issue , it could be a blocked vent line either something in the line or the charcoal canister is plugged
if the purge valve ( Hyundai) is malfunctioning I think it throws a different code
hope this helps

Charcoal canister vent line to this filter ( normally open )

Vapour leak detection pump

Putting pressure into vent line

Vapour leak detection pump

Nitrogen tank with my 1/4 copper line

Charcoal canister Top tube is vent to purge valve into intake Middle tube is tank vent like into canister Bottom tube goes to vapour leak detection pump and into filter in engine passenger side

 

Most of the info that got me started was this guy