2004 Jeep Wrangler Owner's Manual - Page 234
2004 Jeep Wrangler Manual
Page 234 highlights
234 MAINTAINING YOUR VEHICLE Crankcase Emission Control System Proper operation of this system depends on freedom from sticking or plugging due to deposits. As vehicle mileage builds up, the PCV valve and passages may accumulate deposits. If a valve is not working properly, replace it with a new valve. DO NOT ATTEMPT TO CLEAN THE OLD PCV VALVE! Check ventilation hose for indication of damage or plugging deposits. Replace if necessary. Fuel Filter A plugged fuel filter can cause hard starting or limit the speed at which a vehicle can be driven. Should an excessive amount of dirt accumulate in the fuel tank, frequent replacement of the fuel filter which is mounted in the fuel tank may be necessary. Engine Air Cleaner Filter Under normal driving conditions, replace the air filter at the intervals shown on "Maintenance Schedule A." If, however, you drive the vehicle frequently under dusty or severe conditions, the filter element should be inspected periodically and replaced if necessary at the intervals shown on "Maintenance Schedule B." WARNING! The air cleaner can provide protection in the case of engine backfire. Do not remove the air cleaner unless it is necessary for repair or maintenance. Make sure that no one is near the engine compartment before starting the vehicle with the air cleaner removed. Failure to do so can result in serious personal injury. Maintenance-Free Battery Your vehicle is equipped with a maintenance-free battery. You will never have to add water, nor is periodic maintenance required. WARNING! Battery posts, terminals, and related accessories contain lead and lead compounds. Always wash hands after handling the battery.