# Def. poor quality message



## Barry Allen (Apr 18, 2018)

I don't know how, but the car monitors DEF usage to detect "poor quality" of the fluid. I guess it does that to make sure the NOx catalyst functions properly, but also to make sure that cheap SOBs don't just fill the tank with water. Probably is NOx sensors that do a before/after comparison and if the quantity of injected fluid isn't functioning as expected it will give a message.

Sounds like a glitch. If the message vanished, just fill up with good quality DEF. Either a sealed jug from a store, or from any high-volume pump like at a truck stop.


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