As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT#377, BOS-LAS. (ETOPS) ENG 1 IGNITION A FAULT ( IGNITION SYSTEMS A) SYSTEM A ); REMOVED AND REPLACED ENG #1 IGNITION PLUG A IAW AMM 74-21-01. OPS CHECK GOOD. NO FAULTS AT THIS TIME. THIS CLEARS MDDR 524132. PLACARD REMOVED AND MX-4 UPDATED.