You are correct Fargoo … when >127psi detected at High Pressure Controller, servo pressure from HPC is vented to ambient resulting in HPSOV being commanded closed. If HPSOV does not close, EICAS msg appears + Bleed lite.
I understand the system logic ... I'm just wondering why would I have 127+ psi (overpressure as you term it) from 14th stage HP bleed when engines are at low power setting on descent?
(BTW, I didn’t fix it … aircraft was released per MEL 36-11-02)