As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SJC - CREW REPORTED LEFT CONSTANT SPEED DRIVE OVERTEMP INDICATION WITH APU ON PLACARD. EMERGENCY DECLARED FLIGHT RETURNED SJC LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND LEFT CSD OVERSERVICED. DRAINED LEFT CSD TO PROPER LIMIT. REPLACED AUXILIARY POWER UNIT. SYSTEM GROUND CHECK NORMAL OPERATION.