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The simple 2 min. test for egr flow is to hook a hand vac to the egr vac port and pull 15" of vac when the car is at idle .. if the car runs very rough when you apply vac. , you do not have blockage..this also verifies the EGR valve mechanics....so do this test first.
... and an egr code means nothing more than the ecu has detected a fault in the egr SYSTEM,, be it egr valve , ecu sig, switch over valve, tube blockage, vac hose leak, etc, etc ..
Any of these will bring up an EGR code, as the ecu is looking for a vac change when the SOV is sent an electrical EGR application signal.