As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER T/O RECEIVED PAX DOOR LATCH CAUTION, FOLLOWED BY PAX DOOR WARNING MSG'S. EMERGENCY DECLARED, FOLLOWED QRH AND RETURNED TO MSP LANDED SAFELY. INSPECTED PAX DOOR, FOUND SNOW AND GREASE BETWEEN PROX SENSORS AND TARGETS. CLEANED FOD OUT FROM BETWEEN SENSORS AND TARGETS, OPS CHECKED GOOD.