Understanding and Testing the EGR Valve

Find out what it does, how to test it, and what happens if it does not work.

This is a question we get asked almost on a weekly basis. The EGR valve serves a specific function. If not working properly, it can increase exhaust emissions, lower fuel economy, cause rough idle, and carbon up the intake manifold on your engine.

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Problem & Solution

Common among these chassis:

W116
W123
W124
W126
R129
W140
W201

Kent finally decided to do a video due in large part to the questions we receive from our customers. He will explain what the valve does, how it works internally, where it fails, how to test it, and what to do if it is not working.

Note: You will need a hand pump vacuum tester in order to properly test the operation of the valve. See related products as we carry a high quality kit on this website.