As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT NURSE NOTIFIED PILOT OF A BURNING SMELL IN BACK OF CABIN. NO FIRE WARNING INDICATIONS OR ENG INSTRUMENT IRREGULARITIES WERE SHOWING & NO SIGNS OF BURNING SMELL OR FIRE IN COCKPIT UNTIL SEVERAL MINUTES LATER. PILOT WAS BESIEGED WITH A NOXIOUS, CHEMICAL BURNING SMELL, THE AFT CABIN WAS FILLED WITH A HAZY, WHITE SMOKE LEADING TO DESTINATION DIVERSION. DURING TROUBLESHOOTING NOTED THAT THE ECS CONTROL VLV WAS INTERMITTENT IN HOT COLD & REPLACED. ECS WAS WORKING CORRECTLY WITH NO FURTHER FAULTS.