As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: VERY STRONG BURNED OIL LIKE SMELL, IN THE FLIGHT DECK. IT STARTED AT ABOUT 12000 FEET DURING DESCENT. MAINTENANCE FOUND THE APU WAS LEAKING OIL AND REPLACED IT PER TASK CARD 26L31049003. A DECONTAMINATION OF THE ENVIRONMENTAL CONTROL SYSTEM WAS ACCOMPLISHED PER TASK CARD 26L00021014. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO ODORS NOTED.