As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT#1621, LHR-BOS. (ETOPS) 'ENG 2 FIRE LOOP A FAULT ECAM CAUTION MESSAGE APPEARED DURING CRUISE( ENGINE FIRE DETECTION SYSTEMS 1) LOOP A); REMOVED AND REPLACED ENG 2 FIRE/OVERHEAT DETECTOR (4002WD1) PER AMM 26-12-17. THE OPS CHECK IS GOOD.