What does engine emission system failed mean?

Do you unscrew or pull out spark plugs on a vehicle? How do you get to brakes with drum? What is the transmission fluid capacity for a 1986 700r4 trans? Where can you view a 1996 ski-doo formula 3 600 wiring diagram? Fuse box in Chevy Tracker 2002? On a 1988 Toyota Camry what does it mean when the brake the charge and the tail light warning lights come on and all your lights dim and if they dont turn off your battery dies? Where is the fuel pump relay on 1987 GTA Firebird? Where is the fuse for the dashboard lights in a 2003 buick rendezvous? Where is the battery located on a John Deere 2555? Why would your power steering go out after a minor accident and no damage to the pump? Brake fluid filled up to cap what effect would this have on the braking system? Who makes the oil filters for the KIA L engine? How do you replace the lexus rx300 air fuel sensor? Power steering fluid running out I fill the reservoir and it appears to leak out behind the passenger side front tire no warnings noises it just started running out one day Can't tell where from? How does the cassette adapter which can be used to listen MP3 players on your car cassette player work? What would would not be a way you can cut back on your use of oil? How do you remove the Exhaust manifold on a 3000GT SL DOHC? What can happen to a car when an alternator over charges? What is the difference between forward slash and backward slash in command prompt? Replacing ignition lock and tumbler on 85 rx7?