As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, THE LANDING GEAR WAS SLOW TO RETRACT. WHILE CLIMBING AND CONTACTING MAINTENANCE THE OUTFLOW VALVE OPENED AND THE CABIN LOST PRESSURE. AN EMERGENCY WAS DECLARED AND RETURNED TO DEPARTURE. LANDED WITHOUT INCIDENT. ON APPROACH, AN ECAM MESSAGE FOR PILOT ICE FAULT. THE AIRCRAFT WAS GROUNDED. REPLACED NOSE LANDING GEAR PROXIMITY SENSOR IAW AMM 32-31-73. TESTED NORMAL. ACCOMPLISHED GEAR SWINGS IAW AMM 32-31-00. PRESSURED AIRCRAFT IAW AMM 05-53-00. OPS AND LEAK CHECKED NORMAL.