Fuel gauge not going to full.

[Salman90]

Hello everyone, 

I currently own a 2008 Lexus RX400h and I have had this issue with the fuel gauge for over a year now. Every time I fill the tank, the gauge only goes 75% up. However, if the car is parked on a hill facing downwards, the gauge goes to maximum. I have tried filling the tank to the max that fuel started overflowing, but the gauge stayed at 75%. 
Lastly, my hybrid battery indicator only fills up till 80%. It is always on blue, never goes to green. Does this mean the hybrid battery is dying? 
 

Has anyone faced these issues before? Thank you in advance 

[RX400h]

How many miles are on your odometer?

[Salman90]

Around 250k miles 

[RX400h]

That being the case, it would not surprise me if the sender unit needs to be replaced. 

[Salman90]

Thank you for your help.