hello.using an autel 619...abs awd  lights on dash..scanner has 2 codes c1104  and c1108  fr sens 1....and fr sens 2....whats the sens 2  ?      have repalced drivers side sensor used..and a used spindle  was a lot of rust where the sensor would pick up signal...cant erase codes either with tool or by disconecting battery  any help would be appreciated