As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AT CRUISE ALTITUDE ECAM:LAVATORY SMOKE - FORWARD LAVATORY WENT OFF 3 TIMES. NO SMOKE OR FIRE IN LAVATORY. MAINTENANCE REPLACED DECODER ENCODR UNIT B 300RHT (DEU) PER AMM 23-73-47 AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.