What was found
AT FL 350 RECEIVED ECAM CAB/PR EXCESS CAB ALT MASTER WARNING ECAM SHOWING SYSTEM 2 AMBER ON LOWER ECAM THAT WOULD NOT STOP WITH THE WARNING. A SUPPLEMENTAL REPORT TO UPDATE SECTIONS 4 AND 5. REPLACED CPC 1 AND 2 IAW AMM 21-31-34 AND OUTFLOW VALVE IAW AMM 21-31-51. PERFORMED OPERATIONS CHECK OF CPC 1 & 2 IAW AMM 21-31-00-710-002-A, AND 21-31-00-710-003-A. OPS CHECK THE OUTFLOW VALVE IAW AMM 21-31-00-710-002-A, AND 21-31-00-710-003-A. TESTED OK, NO FAULTS NOTED. AIRCRAFT OK FOR CONTINUED SERVICE. THE AIRCRAFT WAS GROUNDED.