It is true that many fansites are allowed to exist they never generally have the exact same domain name with the trademark name so that people may be confused.
Look at the top fansites for any game:
GuildWarsGuru
Runescape.Salmoneus.net
WoWwiki
Tip.it
RuneHQ
RunescapeWiki
EntropiaForum
If you notice maybe they will have the name in there to help people find it and tell them what it is about, but they would never go so far as to take the exact name with which people might use to find the original product, doing that is only courting trouble as it could be that after 2-3 years of building it up and getting it noticed you may end up with a lawyers letter.
A suitable name for you may simply be cod-forum, people then know what they are getting and that you are a fansite...and with a name such as that you will likely get onto the approved list of fansites eventually.
You have taken the exact name people may use to find the original source, hence will find yourself with issues later down the line more than likely as such I cannot say it is worth anything, get a grace delete if you can.
(By the way, even if you sell it, the developers could come after you since you are profiting from the name)