* The fuel level sensor itself: This sensor might be faulty, giving incorrect readings.
* Wiring to the fuel level sensor: A short or break in the wiring can also cause inaccuracies.
* The instrument cluster (gauge): The gauge itself could be malfunctioning.
To fix an inaccurate fuel gauge, you'll need to have a mechanic diagnose and repair the underlying issue. They'll likely need to test the sensor and its wiring.