The spark plugs on a 2002 Nissan Altima 2.5-liter 4-cylinder engine are located on the top of the cylinder head, under the ignition coils. To access the spark plugs, you'll need to remove the ignition coils and the plastic engine cover.
Here are the steps on how to locate the spark plugs:
1. Open the hood of your car.
2. Locate the engine cover, which is a black plastic cover located at the top of the engine.
3. Remove the engine cover by pressing down on the plastic clips that hold it in place and lifting it off.
4. Locate the ignition coils, which are four cylindrical-shaped components connected to the spark plugs.
5. Disconnect the electrical connectors from the ignition coils by pressing down on the tabs and pulling them off.
6. Use a 10mm socket wrench to remove the bolts holding the ignition coils in place.
7. Once the ignition coils are removed, you will see the spark plugs underneath them.
8. Use a spark plug wrench to loosen and remove the spark plugs.
9. Be careful not to drop the spark plugs into the cylinder head.
10. Inspect the spark plugs and replace them if they are worn or damaged.
11. Reinstall the spark plugs, ignition coils, and engine cover in the reverse order of removal.
NOTE: It's recommended to consult the vehicle's service manual or refer to a professional auto technician if you have any doubts or lack experience in performing these tasks. Stay safe and follow proper safety precautions when working on your vehicle.
