As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON ROTATION, AUXILIARY POWER UNIT FAULT LIGHT & LOW OIL PRESS LIGHT ILLUMINATED & APU ROLLED BACK. LT ENG DRIVEN GEN WAS ON PLACARD. FLIGHT RETURNED & LANDED WITHOUT INCIDENT. ACFT REMOVED FROM SERVICE. REPLACED APU MAIN FUEL FILTER. SYS GND CHECKED NORMAL OPERATION CLOSED.