As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DTW - FLT 3395 - ON CLIMB-OUT, CARGO DOOR WARNING LIGHT ILLUMINATED AT 4.5 PSI DIFFERENTAIL. THE CREW REDUCED THE CABIN DIFFERENTIAL AND RETURNED TO DTW. MAINTENANCE REPLACED THE CARGO DOOR HANDLE ASSY. SYSTEM OPERATED SATISFACTORILY. (X)