[rohrmann]

A couple years ago, our DEF tank had to be replaced due to the heater element embedded in the tank had developed an open in the element. A new tank and labor was over $800. The info display said I had 100 miles to go until the speed was restricted to 65 MPH, and counted down as I drove. The dealer I took the truck to had the replacement tank in stock, and that told me this was a common failure on my year. I've never had a problem adding DEF fluid at any time, but usually wait until the display indicates it is at or below 20%, and then I can add two 2 1/2 gallon boxes of fluid.