The spark plugs on a 1999 Nissan Maxima are located at the top of the engine, on the front and rear of the cylinder head. The front spark plugs are located under a plastic cover; the rear spark plugs are located under the intake manifold.
Removal
To remove the front spark plugs:
1. Open the hood and remove the plastic engine cover.
2. Disconnect the coil connectors from the spark plugs.
3. Use a spark plug socket and extension to remove the spark plugs.
To remove the rear spark plugs:
1. Remove the intake manifold.
2. Disconnect the coil connectors from the spark plugs.
3. Use a spark plug socket and extension to remove the spark plugs.
Reinstallation
Note the length and appearance of the old spark plugs. If the old spark plugs are worn or damaged, replace them with new ones of the same size and type.
To reinstall the spark plugs:
1. Screw the spark plugs into the cylinder head by hand until they are finger-tight.
2. Use a spark plug socket and extension to tighten the spark plugs until they are snug.
3. Attach the coil connectors to the spark plugs.
Replacing
* Inspect your spark plugs for wear or damage approximately every 30,000 miles or three years.
* Replace spark plugs when the center electrode measures 0.04 inches (1 mm) or less in diameter or when the spark plugs are damaged.
