As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APPROXIMATELY 12000 FT CREW RECEIVED AN AFT PAX DOOR OPEN WARNING MESSAGE. CREW REPORTED THAT ACFT WAS PRESSURIZING NORMALLY, ELECTED TO RETURN TO DEPARTURE. AN EMERGENCY WAS NOT DECLARED AND CREW LANDED WITHOUT INCIDENT. MAINTENANCE R & R THE LOCK PROXIMITY SWITCH IAW AMM AND OPS CHECKED GOOD. ACFT IS GOOD FOR SERVICE.