Opel ASTRA Owner's Manual page 216

214 Vehicle care
2. Unscrew both screws and remove
light assembly from the bumper.
3. Turn the bulb socket
anticlockwise and remove it from
the reflector housing.
4. Disengage the bulb socket from
the plug connector by pressing
the retaining lug.
5. Remove and replace the bulb
socket with bulb and attach the
plug connector.
6. Insert the bulb socket into the
reflector housing by turning
clockwise and engage.
7. Mount the light assembly by
tightening both screws.
8. Assemble and engage the cover.
4-door notchback
1. Release both caps with a
screwdriver at the marked area.