As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT NR 6424 - IAD-BUF - DURING CLIMB-OUT, RETURNED TO IAD DUE TO THE PASSENGER DOOR WARNING LIGHT ILLUMINATING. AIRCRAFT LANDED AT IAD WITH NO FURTHER INCIDENTS. MX CLEANED AND LUBED THE DOOR MICROSWITCHES. AIRCRAFT WAS RELEASED AND APPROVED FOR RETURN TO SERVICE. (M)