As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: IN ALL PHASE OF FLIGHT A PERSISTENT LIGHT AIR FRAME VIBRATION AND BUFFETING WAS FELT WITH AND WITHOUT AUTOPILOT ENGAGED; AIRCRAFT DIVERTED TO AND LANDED SAFELY AT DFW. INSPECTED AIRCRAFT PER AMM 05-51-67-280-801, FOUND APU DOOR OPEN. NO OTHER DEFECT NOTED AT THIS TIME.