As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE AT GATE WAITING PUSHBACK AFT LAV SMOKE ALARM SOUNDED, ALSO INDICATED ON FAP PANEL AT DOOR 1 LEFT. AIRCRAFT RETURNED TO THE FIELD FOR THIS PROBLEM PER CREW VERBAL ALARM SOUNDED ON CLIMB OUT. FLIGHT CREW REPORTED TO FLAG AS AN SDR. POSSIBLE HAZINESS. CREW SUBMITTED CABIN ODOR FORM, AND NOTED NO UNUSUAL ODORS. REPLACED AFT LAV SMOKE DETECTOR PER AMM 26-17-15-000 AND 26-17-1 5-400. AND REPLACED FILTER. ACP CIDS TEST, TEST PASSED.