Emmissions EGR fault detection is checked by intake manifold pressure sensor [ B5/2] monitoring by the N59 Emmisions Module. If it does not see the required spec. pressure change when EGR Switch-Over-Valve is energized by HFM CU, it triggers the code.
So, on HFM/SFI, an EGR code can be caused by anything from a simple feed line vac leak, SOV, egr, clogged intake tube, .. and on the demand side , a No Electrical Sig from Control Unit.
Always start with the simple test first. [ which is hand vac pump test at idle, right at EGR]