re: DEF fluid fault failure?

Bad def could be the problem. Our local dealer received a bulk tote that would make equipment throw codes. They had to buy a meter that would check the quality of the def. Ended uo changing suppliers after several totes failed the test. We also had a jug that wasn’t sealed good and whatever is in the def that the sensors scan for to make sure you are actually putting def in there evaporated out so the computer thought it was not really def. Drained the tank and put in fresh def and it worked fine.