As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ON DESCENT THROUGH 12000 FEET , STRONG ODOR IN FLIGHT DECK ONLY. MAINTENANCE DETERMINED THE APU OIL SYSTEM HAD BEEN OVERSERVICED, CORRECTLY SERVICED THE APU OIL SYSTEM AND ACCOMPLISHED A DECONTAMINATION OF THE ENVIRONMENTAL CONTROL SYSTEM PER TASK CARD 26L00021013. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO ODORS NOTED.