The thing that the wheel speed sensor reads is called a magnetic tone ring. I have this same issue with mine but I haven't gotten around to replacing the bearing/hub assy. Wonder if my tone ring will look as bas as yours did!
I have an issue with my Volt, occasionally a 'Brake Assist' warning comes on but rarely. The when moving at slow speeds the brakes seem to pulsate when pressing the brake. It is very noticeable when backing out of the driveway. Would this be a symptom of the tone ring needing replacement ?
