As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 3771, CREW REPORTED A THICK HAZE IN THE CABIN AND AN ODOR. MAINTENANCE RAN ENGINES AND PACKS AND FOUND NO HAZE OR ODOR. APU WAS SLOW TO START AND EMITTED A HAZE AND ODOR. REMOVED AND REPLACED APU ASSY IAW AMM 49-10-00. OPS CHECKS GOOD.