How do you replace spark plugs on a 2005 Mazda 3?

To replace the spark plugs on a 2005 Mazda 3, first, ensure the engine is cool and disconnect the negative battery terminal. Remove the engine cover if applicable, then carefully detach the ignition coil connectors and bolts to access the spark plugs. Use a spark plug socket to unscrew the old plugs, and install the new ones by hand tightening initially, followed by a torque wrench to the manufacturer’s specifications. Reattach the ignition coils and connectors, replace the engine cover, and reconnect the battery terminal.