Daniel Mc Laughlin

why does the computor say incorrect DEF quality detected after running for a year on the same tankfull, after a couple of days a new message appears no restarts in 459 miles, is the cars software set to ensure that annually you have to go back to a main dealer. My car is an XE Prestige auto D 180 ps Ingenium engine Nov 66 plate mileage 31890. Danny boy