As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE CLIMBING THROUGH 31,000 FT. WE RECEIVED CAB DIFF WARNING. ABNORMAL PROCEDURES FOLLOWED & WARNING CLEARED SHORTLY AFTER INITIATING A DESCENT TO LOWER ALT. ACFT PRESS WAS CONTROLLED MANUALLY. UNDER DIRECTION OF MOC PERFORMED FAULT ISOLATION OF DIFF PRESS WARNING IAW FIM 21-33-00 & DEFERRED NR 1 ACPC IAW MEL 21-31-1A. INSTALLED PLACARD IN MMO2 NOTIFIED MOC 95765.