Jeep 2005 Liberty Owner's Manual page 282

282 STARTING AND OPERATING
The gas cap is located behind the fuel filler door, on the
left side of the vehicle. If the gas cap is lost or damaged,
be sure the replacement cap has been designed for use
with this vehicle.
When tightening the gas cap, tighten until 2 or 3 clicks
are heard to insure that the cap is properly seated.
NOTE: A loose gas cap may cause the "Malfunction
Indicator Light" to illuminate.
Fuel Filler Cap