ABS Light issue

My abs light likes to come on after about 3 or so miles. But if it don't come then it won't come on at all while driving the rest of the way to the destination. Sometimes it comes on and then sometimes it don't. Could one of the sensors be dirty?

 

Is it before or after anything happens, like after making a right turn or hitting a speed bump or something?

 

it's after I apply my brakes like 3 or so miles after I started driving down the road