As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX - FLIGHT 2555 - AIRCRAFT RETURNED TO FIELD AFTER THE LAVATORY SMOKE DETECTOR SOUNDED AND A SLIGHT ODOR WAS NOTICED. MAINTENANCE GROUND RAN THE AIRCRAFT WITH BOTH PACS RUNNING. COULD NOT DUPLICATE WRITE-UP. NOTED BY MAINTENANCE, THAT THE ENGINES HAD BEEN PRESSURE WASHED THE DAY/EVENING PRIOR TO THE EVENT. OPERATIONAL CHECKS WERE ALL GOOD AND THE AIRCRAFT WAS RETURNED TO SERVICE. NO PARTS WERE REPLACED.