As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX- LEFT HAND LAVATORY SMOKE DETECTOR WENT OFF DURING FLIGHT. NO SMOKE OR OIL FUMES NOTED. AIRCRAFT RETURNED TO FIELD WITHOUT FURTHER INCIDENT. INSPECTED LEFT HAND LAVATORY SMOKE DETECTOR. NO EVIDENCE OF SMOKE OR FIRE. REMOVED AND REPLACED SMOKE DETECTOR, OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.