As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - RECEIVED A APU FAULT MESSAGE ON START-UP. CAUTION THEN WENT AWAY AND THERE WAS A OIL ODOR FROM THE PACKS. MAINTENANCE PERFORMED 3 STARTS OF THE APU WITH NO FAULTS NOTED. THE MDC DATA SHOWED A HUNG START. FOUND NO ODOR IN THE PACKS. APU OPERATES NORMALLY WITH NO DEFECTS NOTED. AIRCRAFT RETURNED TO SERVICE. NO PARTS REPLACED.