Firstly the message is inhibited during phases 3,4,5,7 +8 so i will be off during take off, reappear at cruise and then disappear again below 800ft approach until after roll-out.
The message is generated by a position to selected disagree of the Hot Air PRV. This will always endeavour to keep the pressure 4psi above the cabin px. I would start at the valve not keeping up with this demand during the cabin pressurisation cycles. But without seeing the PFR or TSM it could be anything.
Airbus's always catch the same diseases, we have a fleet of over 70 and they all seem to get a run of the same problems, we have a theory they are either networked or discuss each others ailments on stand.
Good Luck