* Faulty Fuel Sender Unit: This is the most common culprit. The fuel sender unit is located inside the fuel tank and floats on the surface of the gas. It measures the fuel level and sends a signal to the gauge. If the sender unit is malfunctioning (due to corrosion, a broken float, or a faulty sending unit itself), it will send an inaccurate reading.
* Bad Fuel Gauge Cluster: The gauge itself in the instrument cluster could be broken or faulty. It might be receiving the correct signal from the sender unit but displaying it incorrectly.
* Wiring Issues: A broken or corroded wire in the circuit connecting the fuel sender to the gauge can interrupt the signal, leading to an inaccurate reading. This could be anywhere along the wiring path.
* Grounding Problems: A poor ground connection can disrupt the electrical signal, resulting in an inaccurate fuel gauge reading.
* Debris in the Fuel Tank: In rare cases, significant debris in the fuel tank can interfere with the float in the fuel sender, preventing it from moving freely and providing an accurate reading.
* Low-Quality Aftermarket Replacement Parts: If the fuel sender or gauge was recently replaced with an aftermarket part, it might be of inferior quality and not functioning correctly.
To determine the exact cause, a mechanic would need to diagnose the problem. They would likely check the fuel sender unit, the wiring, the gauge itself, and the grounding connections.
