What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND TEH AIRCRAFT RETURNED TO MIA DUE TO A FUEL USED/FUEL ON BOARD DISAGREE ON ECAM IN FLIGHT. CREW SWITCHED BETWEEN OVERIDE PROCEDURE AND FUEL LEAK PROCEDURE MULTIPLE TIMES. AIRCRAFT LANDED SAFELY AT MIA WITHOUT FURTHER INCIDENT. MAINTENANCE CHECKED FOR FUEL LEAKS AND NO LEAKS WERE FOUND. MAINTENANCE ACCOMPLISHED A SATISFACTORY OPERATIONAL TEST OF THE TANK FUEL PROBES WITH NO DEFECTS NOTD. MAINTENANCE WAS NOT ABLE TO IDENTIFY A SPECIFIC PART THE CAUSED THE ECAM MESSAGE.