Hi, from experience I've come to learn when it says quality its not always on about the "quality" of your adblue solution itself, but in fact the quality in which it is injected in to the exhaust system. So when your adblue injector injects, it does this in a fine mist form, but if your injector is failing/faulty, it may dribble out in droplets or be over injecting/under injecting etc, causing the "quality" of the adblue to not meet the specified requirements to be absorbed to reduce the Nox levels which dominos in to causing Nox sensor faults for readings incorrect.
