As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. CABIN PRESSURE "LOW DIFF PRESSURE" MESSAGE DISPLAYED ON DESCENT. JUST PRIOR TO MESSAGE NOTICE CABIN PRESSURE CLIMBING AT 300 FPM UNTIL THE OUTFLOW VALVE OPENED FULLY (AMBER). REPLACED NR 1 CABIN PRESSURE CONTROLLER PER 21-31-34.