I'll try to be concise.   Car: 06 1.9 PD105 BKC   Problem: Goes into limp mode(no MIL) when driven hard, becoming more frequent, cycling ignition clears limp.  Doing this repeatedly shows MIL and maxidot displays 'Workshop Emissions!' requiring DTC 16618 - Charge pressure control; Regulating limit surpassed-Permanent to be cleared.  Odd extended groaning sound on engine switch off.   Action taken: Vacuum hoses checked-ok. Vacuum solenoid block ch