Exhaust Gas RECIRCULATION (EGR)

NOTE: For additional information on EGR system, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section, see below.

Ensure all connections are tight and do not leak. Ensure all vacuum hoses are connected and not kinked. Check EGR function with cold and hot engine at different engine speeds.
With engine coolant temperature below 131°F (55°C), EGR valve should be closed at all engine speeds. If EGR valve is open, replace thermostat valve.
With coolant temperature above 140°F (60°C), EGR valve should only open at partial throttle. If EGR valve remains closed, check thermostat valve by disconnecting vacuum hose from EGR valve and blowing air into it. Air should flow freely through thermostatic valve. If air does not flow freely through thermostatic valve, replace valve.