Gas gauge not working. on 2001 Chevrolet Impala

Gas gauge is not working. How do I know if there is a problem with the gauge or with the sensor? Also, is there a fuse that could cause the gauge to malfunction.

Asked by for the 2001 Chevrolet Impala
When I start my 2oo1 impala it says half a tank but then goes to full.I know it is not full..Any Ideas?
1 more answer , 1 more comment
Most likely it is the gauge, based on the fact that this seems to be a pattern failure with GM. The fuse that powers the fuel gauge powers all the other gauges so if it was bad, none of the gauges would work.
You can check the gauge vs the sending unit in the tank with the data stream of a scanner. You look at reading of the fuel level sensor, if you have a full tank and say it reads 50%, well you know the sender is defective.
I have a 2005 kia sorento and when the gauge gets to 1/2 tank of gas, the fuel lights comes on had the sending unit replace then they say its the dash cluster