Hi, any idea what causes cylinder misfired. i have 2002 cad sts and the engine service light is on and vehicle tends to shake a little while in park or stop. i check and it provides as cylinder 6 misfired. what can happen. would it be the spark plugs. the vehicle is only 63000 miles and thought the plugs are good to 100000 miles. please help.

also, any idea about the security system sensor power low. this system came on asking for service and i checked code and says that the power is low. how can i get it charged to normal power? thanks.

thank you in advance.