As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2129 -EWR- FLIGHT CREW REPORTED THAT PASSENGER NOTICED BURNING ODOR FROM AIR VENTS ABOUT HALFWAY THROUGH FLIGHT, THEN ODOR WENT AWAY. EWR MAINTENANCE PERFORMED OPERATIONAL CHECK OF PACK 1 AND 2 SYSTEM AND NO ODOR WAS DETECTED. ACFT WAS APPROVED TO RETURN TO SERVICE. (S)