Check Valve
WARNING: This page is about a different car, the 2005 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
Check vacuum with a vacuum pump.
CHECK VALVE TESTING CONDITIONS
| Connect to booster side |
Vacuum should exist |
| Connect to engine side |
Vacuum should not exist |
Courtesy of NISSAN MOTOR CO., U.S.A.