As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT RETURNED DUE TO AN AFT LEFT SERVICE DOOR INDICATION. EMERGENCY DECLARED. FLIGHT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS GROUNDED, LEFT AFT CABIN DOOR HANDLE MOVES FREELY WITH DOOR CLOSED AND CABIN PRESSURIZED. REMOVED AND REPLACED L2 DOOR SHAFT ASSY IAW AMM 52-41-11-000-801, SUB TASK 020-001, AND SUBTASK420-005, OPS CHECKED GOOD.