As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX-ON FLIGHT NUMBER 2534, AFTER TAKEOFF, SMOKE AFT LAVATORY WARNING MESSAGE ILLUMINATED WITH NO ASSOCIATED AURAL. WARNING EXTINGUISHED AFTER 15 SECONDS. NO EVIDENCE OF SMOKE/FUMES IN LAVATORY. INSPECTED MDC, NO MESSAGE AND NO HISTORY FOUND. PERFORMED FAULT ISOLATION TASK 26-16-00-810-802. NO DEFECTS NOTED. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.