What was found
AIRCRAFT WAS GROUNDED. EXISTING MEL FOR BRAKE STEERING CONTROL UNIT 1 (BSCU1) WHICH WAS COMPLIED WITH, ON DEPARTURE FROM DFW, RECEIVED A NOSEWHEEL ECAM. COMPLIED WITH QRH, ADVISED DISPATCH, DECLARED AN EMERGENCY AND LANDED AUS. REPLACED SENSOR (4GC) PER AMM 32-51-19. ACCOMPLISHED SATISFACTORY OPERATIONAL CHECK PER AMM 32-51-00-720-003.