As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PIT - FL 91 - AFTER TAKEOFF, CREW RECEIVED THE EICAS MESSAGES 'GEAR DOORS' AND 'GEAR DISAGREE.' THE GEAR AND DOOR AMBER LIGHTS REMAINED ILLUMINATED. FLIGHT RETURNED TO PIT AND LANDED WITH NO FURTHER INCIDENT. MAINTENANCE REPLACED THE NOSE LANDING GEAR DOOR OPERATED SEQUENCE VALVE. (M)