just had the 9xx miles warning on mine as well, but have only gone 1060 miles. Warning went away on restart. I wonder if there is a problem with the pump from main tank to heated tank, or as someone else suggested, a bad sensor? It is above 32 degrees today...

Among the other quirks, the idrive shows your oil level but no engine temp and no urea level. Seems these are two things to keep an eye on... Bet it could be added through programming since the car is tracking both through existing sensors.