As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAV SMOKE WARNING ANNUNICATED IN FLIGHT. WARNING OCCURED W/ PAC IN AFT LAV. FA'S COULD NOT DETERMINE SOURCE OF SMOKE. PAX DENIED USING ANY PRODUCT THAT WOULD HAVE SET IT OFF. ANNUNCIATION LAST FOR ABOUT 30SEC. NO OTHER ANNUNCIATION FOR THE REST OF THE FLIGHT. REMOVED FROM SERVICE. PERFORMED FUNCTIONAL TEST OF AFT LAV SMOKE DETECTOR IAW E175 AMM 26-14-01-720-801-A OPS TEST GOOD. NO DEFECTS NOTED. A/C OKAY FOR SERVICE. RETURNED TO SERVICE.