Fuel Gauge only reads 3/4 full on a fill up on 2005 Land Rover LR3

Whenever I go to fill my tank, it only reads 3/4 full. What is causing it?

Asked by for the 2005 Land Rover LR3
Usually a sign of a bad fuel tank sender unit, better to read inaccurate at that end of the scale than the bottom /empty part.
1 more answer
I had to change my sending unit. But if i don't turn the engine off at fill up it reads 3/4. if you turn it off and start back up it reads correctly.