Chevrolet 1997647 Solenoid Assembly, Egr Control Valve Relay

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The EGR system reduces NOx emissions by recirculating exhaust gas back into the combustion cycle. The EGR valve on the intake manifold should be checked for proper functioning. The engine should lose speed or stall when manually depressing the EGR diaphragm. The vacuum signal to the EGR valve should be checked and the vacuum hose and lines inspected for issues. The thermal vacuum switch regulates the EGR valve based on engine temperature and should be tested with a vacuum gauge. The EGR valve or thermal vacuum switch should be removed following the necessary steps and a new gasket and thread sealer used when reinstalling. The EGR system requires minimal maintenance with occasional inspections of vacuum hoses and valves.

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.

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