As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
COCKPIT ODOR BURNING SMELL. STRONG BURNING ODORS PRESENT BOTH WHEN STARTING THE APU AND THE ENGINES. ODOR SEEMS TO BE STRONGEST AFTER STARTING APU AND SELECTING BLEED AIR ON. REMOVED AND REPLACED HEPA CABIN AIR FILTER. REMOVED HEPA FILTER PN 9914836-1 SN 0093.