As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INTERMITTENT FUMES OF UNKNOWN ORGIN DETECTED IN COCKPIT APPROX 1.5 HOUR INTO FLT FL 360 DEFINITE ODOR LIKE MATCHES/CIGARETTE. LASTED 10-15 SECONDS PAX NOT SMOKING, A/C POWER OFF BRIEFLY DETECTED AGAIN ON DOWNWIND SHORT FINAL & TAXI. AFTER SHUTDOWN, WEAK ODOR IN VICINITY OF VESTIBULE. AFTER INPECTIONS NO DEFECTS NOTED. REF AMM 26-11-00.