As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE A/C WAS IN FOR HEAVY CHECK FOUND THE PAX PSU O2 GENERATOR HAS CORROSION ON VENT VALVE AT 21FD. P/N 802000-23. MX REMOVED AND REPLACED THE PSU O2 GENERATOR IAW EMB 175 AMM 35-20-01. A/C REMAINS IN CMH FOR THE COMPLETION OF THE HEAVY CHECK.