All Def equiped trucks have this function. I have never had any DEF issue, going into my third winter (Canadian) with the 2011 now. I declined the DEF tank insulation cover recall, it would have interfered with my DEF skid plate i installed. Runs like a top, works in -20* weather, and has used 1 gallon for every 1000 miles since brand new , over 150,000 miles ago now. I even forget i have DEF equipment, untill i am reminded it's getting low. Most reliable truck i have owned to date. My previous Dmax trucks were trouble free as well, just didn't handle a load like the new LML platform, i even get 1 mpg better than my LMM, and have more power and torque, and a heavier truck.
x2, but I went with the tank cover. It was -30 here over the weekend and the d-max never skipped a beat. This is by far the best duramax built if you want to leave them stock.
2011 GMC 2500 HD Crew Cab, 20" wheels, ebony leather, and yes it's got a Duramax!!!
SOLD-2005 Crew Cab Regular Box 4wd. Bone stock for the time being.