2003 Pontiac Bonneville Owner's Manual - Page 269

If your vehicle has the optional Driver Information Center (DIC), the CHECK GAS CAP message will be displayed if the fuel cap is not properly reinstalled. If your vehicle has a fuel door lock, the fuel door can be opened manually in case of an electrical power failure. The release mechanism is on the driver's side of the vehicle, at the top of the trunk compartment. Pull the tab to release the fuel door. Notice: If you need a new fuel cap, be sure to get the right type. Your dealer can get one for you. If you get the wrong type, it may not fit properly. This may cause your malfunction indicator lamp to light and may damage your fuel tank and emissions system. See "Malfunction Indicator Lamp" in the Index. Fuel Door Lock On models having the optional theft-deterrent system, the fuel door is locked and unlocked together with the driver's power door lock. To unlock the fuel filler door, use the power door lock button or the remote keyless entry transmitter (if equipped). Notice: Prying on a locked fuel filler door can damage it. Use the remote fuel door manual release located in the trunk in the case of a power failure. 5-10