Correct....the display should tell you when the level drops below 5L..
But it begs the questions of:-
1/ When did you last put fuel in ?
2/ Do you know or have any idea how much fuel you should have in the tank ?
3/ Do you think you should have a lot more fuel in the tank ?
You
MAY have the 'known' problem of the mis-reading fuel gauge..
reading (the blobs of fuel level) to either flash...usually after you have filled the tank,
OR...it to read low all of a sudden when you know there should be a lot more fuel
in the tank (but not full).
I'm sure you have already seen this post/thread.....
https://www.forfour.co.uk/forum/index.php?topic=4481.0