No percentage (unfortunately). When the truck says "less than half" on the display, even though the book says it's a 5gal. tank, wait a while before you try to put a 2.5gal. jug of DEF in it or you'll end up with a quart or so on your boots.
i am having some throttle issues/ loss of power read some nightmare stories online i am hoping its just a def fluid problem? just dropped the truck off at the dealer will find out soon.