How do you remove spark plugs on a 2005 sts Cadillac?

To remove the spark plugs on a 2005 Cadillac STS, first, ensure the engine is cool and disconnect the negative battery cable. Remove the engine cover if necessary, then carefully disconnect the ignition coil connectors and unbolt the coils to access the spark plugs. Use a spark plug socket to carefully unscrew and remove the old spark plugs, taking care not to damage the threads in the cylinder head. Finally, replace the plugs with new ones, reassemble the ignition coils, and reconnect the battery.