What happens when I run out of DEF?

Your truck will start running backwards.

It will slow down(de-rate) intitially, I can't tell what would happen with continued use .

 

The truck will derate and finally come to a full stop. You will then be fired.

 

Depends on how big the DEF tank is and how big your fuel tanks are. Did you fill up twice without getting DEF to bring the DEF level down to half?

You'll probably be ok to skip it. Can you get DEF in the box as an additive when you get fuel? It might be a good idea to try it just so you can keep a box under the bunk.

 

I only put in 51 gallons of fuel so I always have shower credits and I top off the DEF every time.
That way if the def pump is broke or the hose won't reach I still have enough def til my next fuel up

 

Da mn, you need auth for DEF... Not easy being you now.

I usually get it at around 1/2 full indicated. There are some places that don't have bulk, and I wouldn't want to use the box; just looks awkward.

 

I fill def every fuel up. If i fuel at a terminal, they don't all have def and some truck stops have def pumps that can only pump at a trickle so for me it's best to keep it full when I can.

 

There is a yellow light near the DEF gauge that will come on when it gets really low. probably gives you an hour before it starts flashing and derates the motor by 25%. Once it derates you don't want to turn the truck off until you get somewhere that has DEF. It probably won't let you go faster than 5mph if you try to run again without DEF.