As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAVATORY 1F - 2L SMOKE ALARM WENT OFF FOR ABOUT 10-15 SECONDS ON THE GND & SMOKE LAVATORY EICAS MSG CAME ON. PERFORMED TEST OF LAVATORY 1F - 2L SMOKE DETECTOR SYS IAW AMM 26-13-00 WITH NO FAULTS FOUND. PERFORMED FUNCTION TEST ON LAVATORY SMOKE DETECTOR WITH NO FAULTS FOUND. SYS CHECKED NORMAL.