As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FLIGHT ATTENDANT REPORT ODOR IN CABIN DURING BOARDING. MAINTENANCE FOUND APU OIL COOLER LEAKING. OPERATED PACKS OFF OF APU NO ODORS NOTED, VISUAL INSPECTION OF APU ACCOMPLISHED WITH NO LEAKS OR DEFECTS NOTED PER TASK CARD 26L00021002. AIRCRAFT RETURNED TO SERVICE