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It is the SOV that allows the vac to get to the EGR in order for it to open.. The ECM sends an electrical sig to the SOV, not the EGR. So, a bad SOV can cause the code b/c the vac sensor never sees a change if the SOV does not get an ECM signal or does not open when it does gets a signal.
ECM sig mapping for SOV activation is only above coolant temp of 48C, with engine rpms above idle and below WOT w/load mapping from ECM.
Absolute manfold pressure is monitored during those conditions by Diagnostc module for emmissions specs.