Originally Posted by phazerorg
You said you downloaded your ROM from here, but you didn't say which one. There was at least one (Koush's) that was an image of the stock ROM, taken from the OTA update that went out to the phones given out at Google I/O. If you have that ROM (and the corresponding radio), you can just use CWM to install the OTA update. I know this works because I did it myself.
If you really have one of the custom ROMs, your only choice is to return to stock if you want the official OTA. And yes, this will remove CWM and wipe your entire phone (including anything in /sdcard)... so backup anything you want to keep before you try this. See efrant's excellent guide here: http://forum.xda-developers.com/show....php?t=1626895
Sorry man, I know i am not giving a lot of information, but that's cause i really don't know. I did a random "how to update your galaxy nexus to 4.1" tutorial, and i don't even remember where...... I just know the links i download were from here.
So what i am going to do:
1: Factory data reset
2: I think it's going back to ICS
3: Just do the normal system update that should just pop up.
My only fear is if the phone does not ask for update.