Exhaust Gas Recirculation: Testing and Inspection

CHECK EGR SYSTEMS

Vacuum EGR valves can be checked by switching vacuum lines momentarily so that exhaust gas recirculates at idle; if the system is working properly, the engine will stall or run roughly.
Run engine at idle.
Remove EGR control hose from connection near throttle valve:
Check connection on vacuum unit for suction which would indicate a leaking diaphragm or seal.
Connect EGR control hose to available source of engine vacuum:
(vacuum tank or brake booster line).
Engine should stall or run roughly.

If engine does not react during the quick-check:
Bypass EGR temperature switch and repeat test.
If system uses EGR vacuum booster, also check its operation.

If EGR temperature switch and vacuum booster are OK, and engine still does not react during quick-check:
Remove EGR valve and check for blockage and proper seating.
Suck on hose connection and check vacuum unit operation.