It is likely that your fuel sending unit has gone bad. It is located in the fuel tank. Some tanks have an access hole and others require the removal of the fuel tank to replace it.
Bad gauge Bad float in tank
Your fuel sending unit is not giving the correct reading to your gauge
Either the sensor is broken or Your gaug on the dash is not working.
First check the fuse for the 2003 Cavalier gauge. Next check the fuel sending unit in the fuel tank to insure that its working properly. Check the gauge next, then the wiring for the system. One of these units is causing your gauge to not work.
The fuel sending unit for the fuel gauge would be located in the fuel tank.
fuel gauge not working
fuel sending unit broken wire or gauge is bad
the float could stick
Either the gauge is broken or the sender is broken.
There is none. But you can try disconnecting the wiring attached to the fuel sending unit and look at the fuel gauge. If it is giving you an empty reading, the fuel gauge is faulty and should be replaced.
Look for a bad grounding wire. If the fule gauge sending unti is properly gounded, it should send the signal to the fuel gauge, make sure the fuel gauge is grounded. You may have a bad fuel gauge.
On a car, there is a float inside your gas tank. It is attached to a switch that sends the empty.....full signals to your fuel gauge.