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Vacuum tester and alternatives available here https://amzn.to/2JUwETW
A simple way to test this common and important component.
*IMPORTANT* This particular valve switches and diverts vacuum at 1000 rpm and this is controlled by the ECU so it is important to check for your own vehicle, the circumstances under which your valve is supposed to work. As an Amazon Associate I earn from qualifying purchases. Using my Amazon links does not cost you any extra.