As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ON INITIAL TAXI WITH POWER UP GOT DIRTY SOCK SMELL IN COCKPIT. FLIGHT ATTENDANTS DID NOT SMELL. DISSIPATED ON TAKEOFF ROLL SMELL BEGAN AGAIN AND STRONGER. FROM GASPER VENTS. FLIGHT ATTENDANTS DETECTED SMELL DIRTY SOCKS FOR 5 MINUTES, THEN DISSIPATED MILD ODOR. REPLACED AUXILIARY POWER UNIT.