Honda 2003 Civic GX Owner's Manual Supplement page 11

Refueling Procedure
5. Securely connect the CNG fill
nozzle to the fuel receptacle by
turning the lever until the arrows
on the nozzle point to each other.
10
Before Driving
6. Follow the instructions on the
refueling station to begin refueling.
While refueling, you may hear a
chattering sound. This is normal.
If you hear or see fuel/vapor
leaking from the nozzle-receptacle
connection, stop refueling
immediately. Dirt or other debris
may be preventing a positive
connection. Turn off the refueling
station, remove the nozzle,
reconnect it to the receptacle, and
begin refueling again. If it
continues to leak, have an
authorized Honda Civic GX dealer
inspect the sealing O-ring in the
receptacle for damage and wear.
7. Refueling will stop automatically
when the tank is full. Follow the
instructions on the refueling
station to turn it off.
Disconnect the CNG fill nozzle
8.
from the fuel receptacle by
turning the lever on the nozzle 180
degrees. You may hear a brief
hissing sound as a small amount of
gas escapes. This is normal.