how do you go about changing the ABS sensor, if possible where is it and how hard is it to replace???

You have wheel speed sensors in all 4 hubs. You must replace the whole hub/bearing assembly.

Offhand, can you tell us how you know it'* a sensor? Did you have it diagnosed?

thats what i was told, i want to get an early jump on it if that is what the problem is.

But how do you know it'* one of the sensors, and do you know which one? Only the dealer can scan for those codes. Otherwise, you could spend an enormous sum of money and never fix the problem.

I'm not so sure that the hubs need to be replaced. Here'* a pic of the hub and the sensor ring. The ring was press fit into the spindle:

i have never had to work on an abs sensor, i'll get it figured out, thanks for the tips all.

Even the sensors alone are a bit pricey:

rear
GM PART # 10457129
CATEGORY: Electronic Brake Control
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $104.66
OUR PRICE: $52.33
DESCRIPTION: SENSOR AS

The part number for the front comes up as 10457144 during a search but I couldn't find a price on it. Personally, I'd do as willwren suggested and find out which one(*) are at fault first before replacing every sensor.