As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6276 - IAD-EWR - DURING TAXI, RETURNED TO GATE DUE TO LEFT DUCT FAIL LIGHT ILLUMINATED. AIRCRAFT RETURNED TO GATE WITH NO FURTHER INCIDENTS. MAINTENANCE REMOVED AND REPLACED O-RING ON BLEED AIR SUPPLY LINE, OPS CHECK OK. AIRCRAFT WAS RELEASED AND APPROVED FOR SERVICE. (M)