Software issue?

[PeggyLee]

We have a VW Passat 2014, driving up north with my
grandkids, light comes on to Add Def, I added Def
the light stays on (wrench) says I have 150 miles
before engine shuts off. Now I'm down to 80 miles
before engine shuts off! I filled it up! Is this a glitch in
software? I can't take a chance in 7 degree weather
with grandchildren on highway! Help!

 

[Lightflyer1]

Generally from my reading here, it is a hardware issue with the DEF tank system itself. It should be covered under the Extended Emissions Warranty if it is still in effect for your car. This assumes this is the first warning you have shown. Normally it would come on at some greater distance to empty and then count down. A sudden appearance at a low mileage is an indication of an abnormal issue. Check your car here for warranty coverage.

VW Emissions Modification Lookup

www.vwdieselinfo.com

Engine will continue running until you shut off and then won't restart until fixed, once the countdown is reached. Def also freezes at low temps (11F) and you may be experiencing that as well. It may be freezing and the heater doesn't work to keep it liquid. Have the dealer do the work if covered. Get to know the warranty and what the terms are if you plan to use it. Have a copy with you when you go in just in case. You should get a rental for free too if they need to keep it for a while.