abs light is on, i got it smogged and the guy told me it went off after only 2 wheels was moving, the light went back on after all wheels was moving and said it may of been something wrong with the rear sensor i could couldnt understand the guy that good so what was he trying to say is wrong with it? is there something i can check first before i go get it scanned?

 

IF you can get the scan done for free, do it. That will tell you where to start looking. Wheel speed sensors are common failure items, and will most assuredly confuse the ABS. (turn on the lite)