As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MASTER WARNING ON EICAS LAV SMOKE AFT FA REPORTED THAT HE HEARD A SQUEAL LIKE SOUND FROM THE AFT LAV. REMOVED FROM SERVICE. PER VERBAL CONSULT WITH CREW, CONFIRMED THERE WAS NO SMOKE ODOR COMING FROM LAV. REPLACED AFT LAV SMOKE DETECTOR REF TASK 23-14-01-000-801-A AND 26-14-01-400-801-A OPS CHECK GOOD. RETURNED TO SERVICE.