The fuel gauge is stuck on Full.
This problem may be due to a fuel gauge sender malfunction, which is fairly common, or it could stem from the motors behind the instrument cluster that move the gauge needles.
The fuel gauge sender is typically found in the gas tank, along with the fuel pump module. Keep in mind that it may not be necessary to drop the gas tank for a visual inspection; an experienced mechanic with the proper scanner can read data coming from the sensor to pinpoint the failure.
I would suggest that you consult a mechanic, like the ones at YourMechanic, for a thorough fuel gauge diagnosis.
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