fuel gauge

My son bought a new 2005 Titan and the fuel gauge doesn't work. It shows a full tank. Of course, its in warranty and can get it fixed but curious if there's something he can check ( fuse, connector, etc) to avoid having to give up the truck for a minor thing that he can easily fix himself. Appreciate any insight you may give.

Update to my previous post. The sending unit in the tank had to be replaced. All better now.

I have the same problem with my "04. Last weekend the gauge began to read fully after 4 days on the road (yeah right). My question is does anyone know who would sell the sending unit (not the whole pump) besides a dealer (we're in a recession guys :cool:)? I've begin searching the web but found nothing so far. Thanks in advance.