Thanks for all your help!! I change out the board about a month ago but don’t recall getting any codes...Luckily, it’s working fine on LPG, so I’ll do some trouble shooting tomorrow!
Last year the 621 in our Eagle Cap failed on AC (but with an AC relay stuck code). Maybe we got bad relays from the same batch? :D. Check out the fuse and element itself but if those check out OK, check out my $5.80 relay replacement here: https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29727778.cfm