Check Valve For EVAP Vacuum Control Circuit
WARNING: This page is about a different car, the 1995 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
Remove check valve. See COMPONENT LOCATIONS under INTRODUCTION. Air should flow from Blue port to Black port. Air should not flow from Black port to Blue port. Replace check valve if it does not operate as specified. Install check valve with Blue port toward intake manifold.