Did the MFD advise to fill 10 litres ?Did you get it fixed? We have had the same experience with the drop and the alert. We filled the tank with 10l and the alert Is remaining after 32 miles. Not sure if it needs to go in to a dealer to check. We are sadly out of warranty.

Siphon it offProbably being daft. To lower the level, is it a matter of siphoning it off?
I didn’t check how much was needed, just thought that it was better in the tank than in the bottle and if it was too much, it would over flow.

Nothing relating to adding AdBlue is obvious… I’ve had the van for 1.5 years and still no sign of needing to add Adblue as of yet… this aspect of the van continues to remain a mystery to me atm…Did the MFD advise to fill 10 litres ?
Did you turn off ignition whilst filling , parked flat and level, after filling the required amount advised by the MFD, turn on ignition to first position, wait 30 seconds for the add blue to recalibrate?
Assuming you've not overfilled the Ad blue tank ?
try adding the anti Cystallisant
If overfilled reduce the level
What does the MFD show regarding range left after filling ?
What did it show before filling?
Any change ?
I'm pretty sure the Add blue system will periodically recalibrate whilst driving , which may sort it out.
Can you force a Regen ? (OBD tool) which would obviously force usage of Add blue.
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