2004 VW Jetta - where is the fuel door release button in trunk?

Remove the carpeted panel on the fuel door side inside the trunk. There will be a string or cable - pull that to release the fuel flap. If there's nothing wrong with your central locking, just unlock the car as usual and press on the rear edge of the flap to pop it open.

@Harley - What if the central locking motor for the fuel flap has failed?

The only fuel door release button is in the driver's door panel. There is no Emergency Release Handle in the trunk. If the fuel door doesn't open when you use the button on the driver's door panel, something is broken.

You should see a mechanic. The problem could be one of several things, most likely the button is bad, or the actuator motor is bad. 50/50, either one.

If the actuator motor is the problem, replace it AND the guide sleeve.

If the fuel door is plastic, you can pop it open with a plastic rod or spoon. A metal fuel door will not pop open without damaging it and/or the fender.

Door Release Button

the fuel door is released by the central locking