2018 Q5 sport AdBlue/DEF fault no restart in 650 miles

[Paul Blue]

Hi all I’m new to the forum.  I have this car about 3 years or so and the current mileage is about 66k, and it has given me no issues until about 3 weeks ago.  I have the AdBlue/DEF fault appear which was quite concerning.  However since it first displayed until the present it appears and disappears frequently. When it reappears it’s back at the 650 miles again, the lowest it got to was 600 miles and on the next restart it had cleared again.  Just to confuse things further around the same time (can’t remember which came first) the car developed 2 other issues, my front parking sensors stopped working for a time but are now working again, and on starting the car my drivers side door mirror stays in the parked (shut) position.  I have to select the close position on the door control so both mirrors are in the closed position then open both again from the door control.

If you are still reading this thanks, as I’m totally confused typing this as its such a weird set of issues.  Not sure if they are related or not, but I would be very happy to receive any observations.  
To me it seems like an electronic issue.