As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG UNPLEASANT ODOR REPORTED THROUGHOUT THE AFT SECTION OF THE AIRCRAFT. AIRCRAFT WAS GROUNDED. MAINTENANCE FOUND THE LAVATORY SINKS BACKING UP IN COACH TOILETS AND REPLACED THE RELAY IAW WDM STANDARD PRACTICES 20-15-46, AND PERFORMED SATISFACTORY OPERATIONAL CHECK.