97 sunfire gt probs

hey theres a few problems im having and some help would be greatly appreciated....first off....a squeeling problem from the wheels...the brakes aren't worn down...theyre still greater than 50% is what the inspection guy told me..im thinking theyre rubbing somewhere but i dont know exactly how i could fix it....two i have my check engine light and ets light on....ive taken it back to the guy that sold it to me...he checked it with the handheld comp and said it was an 02 sensor...which he replaced...but now it came back on just gimme some feedback if you know what could be the problem...thanks

I would bet you have a hub bearing going bad. The ETS light is the traction control. When the hub start to go bad, it causes that wheel to drag, giving unequal wheel speed readings to the ABS computer, tripping the ETS light. The hub bearing will start to squeak or squeal when they go