As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
F/O SMELLED SOMETHING ABNORMAL JUST A MOMENT PRIOR TO AVIONICS SMOKE INDICATION DURING TAXI-OUT. SUBSEQUENT CHECK OF SNIFFER FAN WAS NEGATIVE FOR SMOKE OR FUMES. WARNING EXTINGUISHED AFTER APPROX 2 MINUTES. CHECKED AVIONICS AREA WITH SEVERAL SYSTEMS ON, COMPLETED VISUAL ALSO. NO INDICATION OF SMOKE DETECTED .NO ODORS OR SMOKE NOTED.NO FURTHER INDICATIONS.OK FOR SERVICE.