As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: MUSTY, DIRTY SOCK ODOR THROUGHOUT ENTIRE AIRCRAFT IN FLIGHT REPORTED BY FLIGHT ATTENDANTS. THE ODOR WAS ALSO FAIRLY STRONG IN THE FLIGHT DECK. IT WASN'T NOTICEABLE ON THE GROUND WITH THE APU RUNNING. MAINTENANCE FOUND THE PLENUM SEAL LEAKING AND ALSO AN INTERNAL LEAK OF THE APU AND REPLACED APU.