Spark plugs are on the sides of the engine and replacing them usually need a spark plug socket that screws onto a ratchet, assorted sockets and extension bars and a gap gauge to check and set the gaps on the new spark plugs. A special plug wire removal tool may be used to pull the wire boots away from the spark plugs though it is not necessary and a torque wrench should be used when tightening the new plugs. And while it is recommended to buy new plugs in advance and gaped appropriately to be put into the cylinder one at a time, it is essential to be sure of the type of plug bought, having regard to the information on the Vehicle Emission Control Information label. The engine should be allowed to cool before removing it and before installation of the new plugs they should be inspected for any defect and the gaps should be set using a suitable gauge. During the process of pulling the spark plug wire, do not pull the spark plug instead pull only on the boot and blow the spark plug hole with compressed air to clean it. Upon pulling the old plug analyze it against a 'condition chart' to determine the running condition of the engine, then screw in a new plug into the hole and fasten it tightly with an aid of a torque wrench/ratchet together with a rubber hose if possible. Check the spark plug wire before connecting it to the new plug, hose the boot with silicone dielectric compound before connecting it to the plug. Fuse connection and spark plug wires should be inspected and should be replaced if damaged; visual tests should be performed when the engine is running exposing it to visible sparks or other forms of damages. Every wire should be checked out separately with the beginning at the first cylinder and to be marked so that there will be no mixing during the connection. Sometimes you just have to clean up the wires, inspect for any form of damage and make sure that they sit tightly on both ends depending on where they connect; the spark plug or the ignition coil pack. In the event of new wires necessary, it is advisable to obtain the correct wires corresponding to the particular engine type, and swap these wires individualistically so as not to mistake them.