How Does a Gas Gauge Work?

Gas Gauge Basics
1. An automotive gas gauge works by electricity, and displays the amount of gasoline inside a car's gas tank. Located directly on a car's dashboard, a gas gauge normally breaks the fuel level readings down into quarter increments: Empty, 1/4, 1/2, 3/4 and Full. Most gas gauges use a small needle to pinpoint the exact fuel level.
Gas Gauge Receives Info From Gas Tank
2. A gas gauge is connected by electrical wiring to the fuel sending unit, which is a device located directly inside a car's gas tank that directly measures fuel level. The fuel sending unit adjusts to the level of gasoline inside the tank, and it relays this information, via electrical impulses, directly to the gas gauge on a car's dashboard.
Low Fuel Warning Light
3. Most cars are equipped with gas gauges that have a special warning light, or reading, designed to illuminate when the fuel in the tank becomes dangerously low. This is designed to catch the driver's attention by making the gas gauge stand out. The warning light is generally designed to come on when there is less than 1 gallon of fuel left in the tank.