As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT THE AIRCRAFTS PRESSURIZATION INDICATOR DID NOT SHOW CABIN PRESSURE ON NEEDLES, BUT THE AIRCRAFT WAS PRESSURIZED. THEY DIVERTED BACK TO THE AIRPORT FOR REPAIRS. THE MAINTENANCE PROVIDER REMOVED AND REPLACED THE CABIN ALTITUDE DIFFERENTIAL PRESSURE GAUGE WITH AN OVERHAULED UNIT. OPS CHECKS WERE SATISFACTORY, AND THE AIRCRAFT WAS RETURNED TO SERVICE.