How do replace the spark plugs on a 1999 Qx4 infiniti?

To replace the spark plugs on a 1999 Infiniti QX4, first, ensure the engine is cool and disconnect the negative battery terminal. Remove the engine cover if necessary, then carefully detach the ignition coil connectors and unscrew the coils. Use a spark plug socket to remove the old spark plugs and replace them with new ones, ensuring they are properly gapped. Reassemble by reattaching the ignition coils and battery terminal.