As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2306 - EWR - FLIGHT CREW REPORTED CABIN ALTITUDE SHOWING DASHES. CREW PERFORMED AIR RETURN AND LANDED AIRCRAFT WITHOUT INCIDENT. EWR MX REMOVED AND REPLACED ELECTRO-PNEUMATIC OUTFLOW VALVE AND DIGITAL PRESSURE CONTROLLER. MX PERFORMED OPERATIONAL CHECK SUCCESSFULLY. AIRCRAFT WAS APPROVED TO RETURN TO SERVICE. ELECTRO-PNEUMATIC OUTFLOW VALVE INFORMATION REPORTED ON SDR C2XA08R1097. (A)