Fuel Level Sending Unit
A sensor inside the fuel tank that uses a float to measure the fuel level and display it on the dashboard gauge.
The fuel level sending unit is a sensor located inside the fuel tank, typically integrated with the fuel pump assembly. It consists of a float attached to a metal rod that rides on the surface of the fuel. As the fuel level changes, the float moves, adjusting a variable resistor.
This change in electrical resistance alters the voltage signal sent to the instrument cluster, which moves the needle on the dashboard fuel gauge or updates the digital fuel range display. Over time, the contact fingers on the variable resistor can wear out or become coated with sulfur deposits from fuel.
A failing sending unit can cause the fuel gauge to behave erratically—such as displaying full when the tank is empty, dropping suddenly, or remaining stuck on one level. Replacing the sending unit usually requires dropping the fuel tank or accessing it through a panel under the rear seat.