I have had to become rather insistent that the dealership service department completely "fill" the DEF tank. I also insist, before I take it in, that they have sufficient diesel oil & DEF on hand. I am not customarily so demanding, nor do I usually need to be. Now, I am acquainted with both the service rep. and service manager. Some of the initial issue seems to have been that this dealership, perhaps many others, were not in the beginning well prepared to service JGC diesels. Things seem to be more on course, now, after my initial frustration with Jeep and the dealership service. By the way, often the DEF display takes a while to reset. So, the service tech may be estimating how much DEF is required rather than filling until it overflows. DEF, I'm told, is a rather messy liquid.