How to Unlock a Gas Door Lock on a Mercedes Benz S320
1. Locate your Mercedes SmartKey, which locks, unlocks and starts the vehicle. 2. Press the unlock button on your SmartKey. The unlock button has an open padlock on it. If you press the button once, the drivers door and the fuel filler door open. Pressing the unlock button twice will also unlock the fuel filler door as well as the passenger doors. 3. Press the right side of your fuel filler door to open it.