As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4086 WHILE DESCENDING INTO ORD THE CREW NOTICED A WET SOCK ODOR. THE ODOR WAS ONLY NOTICED IN THE COCKPIT. THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE 0 CARBON SEAL ON THE LEFT ENGINE IAW RR MM 72-25-25. NO MORE "WET SOCK SMELL" NOTICED AT THIS TIME. THE AIRCRAFT WAS RETURNED TO SERVICE.