2008 Jeep Grand Cherokee Owner's Manual - Page 400

400 MAINTAINING YOUR VEHICLE NOTE: Intentional tampering with emissions control systems can result in civil penalties being assessed against you. To minimize the possibility of catalytic converter damage: • Do not shut off the engine or interrupt the ignition when the transmission is in gear and the vehicle is in motion. • Do not try to start the engine by pushing or towing the vehicle. • Do not idle the engine with any spark plug wires disconnected or removed, such as when diagnostic testing, or for prolonged periods during very rough idle or malfunctioning operating conditions. 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! WARNING! A hot exhaust system can start a fire if you park over materials that can burn. Such materials might be grass or leaves coming into contact with your exhaust system. Do not park or operate your vehicle in areas where your exhaust system can contact anything that can burn. In unusual situations involving grossly malfunctioning engine operation, a scorching odor may suggest severe and abnormal catalyst overheating. If this occurs, stop the vehicle, turn off the engine and allow it to cool. Service, including a tune up to manufacturer's specifications, should be obtained immediately.