Strange one last weekend. Saturday morning on way to classic bike show at Stafford and the Ad Blue warning comes up , 650 miles remaining. Ok no problem only 50 miles back that night so can top up then. Set off that evening and scrolling the MFD the Ad blue light has gone off and says 5000 miles remaining. Only difference was it was about freezing in the morning and the van was in the sun all day. No warning going back on Sunday or since.