Why will the gas gauge not read that you have almost a half a tank of gas?

The gas gauge may not read accurately due to a faulty fuel sending unit, which is responsible for measuring the fuel level in the tank. Additionally, the gauge itself could be malfunctioning, or there may be issues with the wiring or connections between the sending unit and the gauge. Temperature changes can also affect fuel density, leading to fluctuations in readings. Lastly, if the vehicle is on an incline, it may cause the fuel to settle unevenly, impacting the gauge’s accuracy.