As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AIRCRAFT ODOR, SOURCE UNKNOWN, STRONGEST MID TO AFT CABIN. MAINTENANCE ISOLATED THE SOURCE OF THE ODOR TO THE MID LAVATORY TOILET ASSEMBLY THAT WAS LEAKING AND REPLACED IT PER AMM 38-31-41. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED.