As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, LANDING GEAR DOOR OPEN LIGHT REMAINED ILLUMINATED AFTER LANDING GEAR RETRACTION. RECYCLED LANDING GEAR AND LIGHT REMAINED ILLUMINATED. AIRCRAFT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. REPLACED LEFT MAIN LANDING GEAR DOOR WARNING SWITCH AND OPERATIONAL CHECK GOOD.