As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BWI - CREW REPORTED AFTER TAKEOFF PRESSURIZATION FLOW LIGHT ILLUMINATED. EMERGENCY DECLARED FLIGHT RETURNED BWI LANDED WITHOUT INCIDENT. CLEANED BOTH PACK AIR CYCLE MACHINE DE-ICE TUBES. PRESSURIZED AIRCRAFT AND NO FAULTS FOUND. SYSTEM GROUND CHECK NORMAL OPERATION.