As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: DIRTY SOCK SMELL IN FLIGHT DECK ESPECIALLY WITH ENGINES AT IDLE DURING DESCENT TRIED TURNING NUMBER 2 BLEED OFF NO REAL CHANGE. MAINTENANCE HAS ISOLATED TO THE SOURCE OF THE ODOR TO THE APU. REPLACED APU AND ACCOMPLISHED A SATISFACTORY LEAK / OPERATIONAL CHECK PER TASK CARD 26L31049003.