your tank size 12.5 L is correct - its 3.3 gallon
have you rode the scoot more then 31 miles yet ??
the instructions say to add at least 2 gallon of gas to the tank once installed to update the fuel and range displays
if it does not update quickly - it will update after 31 miles
and also says the tank needs at least to be filled half way before it will update
it will learn your ride style and update according to that .. as far as the light
it says nothing
another member replied Many members had the same experience of not working til after a fill up or 2.
go read here
http://www.hdforums.com/forum/dyna-g...t-working.html