As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL 430 4 HOURS INTO FLIGHT CREW DETECTED ELECTRICAL BURNING ODOR FROM CREW REST AREA. SMOKE EMERGENCY PROCEDURES WERE INIATED. AFTER PULLING GALLEY CB'S AND TURNING RECIRCULATION FANS OFF ODOR DISSIPATED AND THEN RETURNED. EMERGENCY DECLARED AND DIVERTED WITHOUT FURTHER INCIDENT. MAINTENANCE DISCOVERED FAILED FORWARD WATER TANK LEVEL SENSORS WHICH WERE CHANGED AND THE AIRCRAFT RETURNED TO SERVICE. MANUFACTURER NOTIFIED OF OCCURRENCE FOR DISPOSITION.