Oldsmobile/Buick Repair: in put speed sensors, speed sensors, antilock brakes

Question
-what it is
-how hard it is to fix i mean replace if it is requiered
-what is its effect on emission teast

Answer
hey biz.well a input speed sensor is a sensor used to tell the computer how fast the wheels or transmission is going.but their is two kinds one is mounted on the wheel or hub .this is a abs sensor for antilock brakes.this one has no effect on emissions..the other simply tells your speedometer how fast you are driveing .this one also has no effect on the emissions..hope this helps  billy mac