As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4586 THE CREW REPORTED THAT DURING DESCENT INTO LGA NOTICED AN OVERHEAT/AIR BURNING SMELL IN THE COCKPIT. THE AIRCRAFT WAS REMOVED FROM SERVICE. PERFORMED HIGH POWER ENGINE RUNS & CHECKED AIR CIRCULATION MACHINE’S FROM ALL BLEED SOURCES. MAINTENANCE COULD NOT DUPLICATE THE ODOR. CHECKED INLETS & EXHAUST FOR EVIDENCE OF OIL, NONE NOTED. THE AIRCRAFT WAS RETURNED TO SERVICE.