Chevrolet 1997647 Solenoid Assembly, Egr Control Valve Relay

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With the engine cold to prevent burns, you can reach under the EGR valve and manually push on the diaphragm. Using moderate pressure, you should be able to press the diaphragm up and down within the housing.

The EGR system does not operate at idle or during deceleration.

The two types of EGR valves used are negative backpressure and positive backpressure.

The EGR valve, located on the intake manifold, is the heart of the EGR system. It should be checked for proper functioning.

The exhaust gas recirculation (EGR) system is used to reduce the emissions of oxides of nitrogen (NOx) from the exhaust. It works by recirculating a small amount of exhaust gas back into the combustion cycle to lower peak temperatures and reduce the formation of NOx. The EGR valve, located on the intake manifold, is the heart of the system and should be checked for proper functioning. By manually depressing the EGR diaphragm, the engine should lose speed or stall, indicating that the valve is working correctly. The vacuum signal to the EGR valve should also be checked, and if there is no vacuum, the vacuum hose and lines should be inspected for any issues. The EGR system also uses a thermal vacuum switch to regulate the EGR valve operation based on engine temperature. This switch should be tested with a vacuum gauge and replaced if it is defective. If the EGR valve or thermal vacuum switch needs to be removed, the necessary steps should be followed, and when reinstalling, a new gasket and thread sealer should be used. Overall, the EGR system requires minimal maintenance, with occasional inspections of the vacuum hoses and valves.

If the diaphragm does not move or moves only with much effort, it is recommended to replace the EGR valve with a new one.