Cadillac 2000 Catera Owner's Manual page 250

The cap is behind a hinged door on the passenger's side
of your vehicle.
6-6
You can also press the fuel button on the remote keyless
entry transmitter to access the fuel cap.
To open your fuel door,
your vehicle must be in
PARK (P). Press the
FUEL DOOR unlock
button located on the
instrument panel center
console to unlock and
open the fuel door.