As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: LAVATORY SMOKE DETECTOR AURAL AND ASSOCIATED EICAS MSG BEGAN AT 15000 FEET FOR LAVATORY 3F-1 AND 2. FIM TASK 26-14-00-810-808, OBSERVED NO MAINTENANCE ACTION IS NECESSARY, LAVATORY SMOKE DETECTION OPERATIONAL TEST IAW AMM 26-13-00-710-801 CARRIED OUT AND PASSED SUCESSFULY.