It's an emissions violation, that's why. Yes it should be better documented. I ran into this as well on my Subaru, but once the cap is on proper it -should- tu

It's an emissions violation, that's why. Yes it should be better documented. I ran into this as well on my Subaru, but once the cap is on proper it -should- turn off within ~1hr of driving (constant or short trips) To wit; if you don't put AdBlue in a diesel it will eventually outright stop working altogether even though it's only there for emissions.