Definition & Meaning of "filler cap"in English

What is a "filler cap"?

A filler cap is a cover that seals the opening where fuel is added to a vehicle's tank. It is usually located on the side of the car, often near the rear, and can be twisted or popped open to allow access for refueling. The cap helps prevent fuel from spilling out and keeps dirt and debris from entering the tank. It also helps maintain proper pressure within the fuel system. Filler caps may have a safety feature to prevent the tank from overfilling and are often designed to lock to prevent tampering.