As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT NOT GROUNDED: PILOT REPORTS DURING CRUISE, PAX AT SEAT 23B REPORTED SMELL OF BURNING RUBBER F/A CONFIRMED SMELL. MAINTENANCE ACCOMPLISHED CABIN ODOR TROUBLESHOOTING TASK CARD 26L00021001 FLIGHT CREW RAN ENGINES AT GATE WITH NO FAULTS OR ODORS NOTED.