Test Number 1)

Plugged Intake Passage - Shut off engine, and remove EGR valve. Plug exhaust side port using a shop rag or suitable plug. Attempt to start engine. If engine runs at a very high idle (up to 3000 RPM is possible) or if engine starts and stalls, EGR intake passage is not plugged. If vehicle starts and idles normally, intake side passage is plugged.

Plugged Exhaust Passage - With EGR valve removed, plug intake manifold side passage using a suitable plug. Start engine and listen for exhaust noise. If no exhaust gas escapes from open EGR port, exhaust passage is plugged.