As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHX - CREW REPORTED SMOKE IN THE CABIN. EMERGENCY DECLARED FLIGHT RETURNED PHX LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND OIL LEAKING FROM AUXILIARY POWER UNIT. REPLACED APU AND ACCOMPLISHED PACK BURN. SYSTEM GROUND CHECK NORMAL OPERATION.