To open, unlock the fuel tank door with the key, turn the fuel tank cap counterclockwise and remove it.
If a slight hiss is heard when the cover is removed, this is normal. When closing the screw cap, make sure that the cap escutcheon fits into the notches of the nozzle.
Make sure the screw cap is properly fitted and tightened to prevent fuel from escaping in the event of a collision.
Use only genuine Toyota screw caps as replacements. They are equipped with an integrated vacuum valve.