why is gauge saying low fuel and I just filled it up? on 2006 Chevrolet Uplander

This is the second time instead of fuel gauge reading full it is reading low miles seems like gas needle went wrong way

Asked by for the 2006 Chevrolet Uplander
There could be a problem with the fuel sending unit in the tank, a problem with the gauge itself, or a problem with the wiring that sends the information. Typically the lower the gauge, the less resistance is present from the sending unit. Have the unit checked.