Many many things about check engine light
Once home, the next step is to jack up your car and pull off the wheel. You will have completed the bulk of your brake repair with these two tasks. If you still are not sure that brake repair is necessary, you can eyeball the pads through the brake housing view port before removing the wheel. Once you determine that brake repair is necessary, then remove the wheel and the lower bolt on the brake housing and swing the unit up and away from the wheel. Now you can begin the actual brake repair.