As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OUTFLOW VALVE INDICATOR FLUCTUATES INTERMITTENTLY BETWEEN NORMAL POSITION TOWARDS OPEN, CABIN ALT AND DIFF PRESSURE STAYS STEADY, CABIN RATE OF CLIMB WOULD INTERMITTINGLY FLUCTUATE PLUS AND MINUS 400' IN BOTH AUTO AND ALT. GROUNDED - YES. ON DEFERRAL.