Suzuki WagonR+ RB310 Service Manual page 895

6E2-46 ENGINE AND EMISSION CONTROL SYSTEM (M13 ENGINE)
6) After checking vacuum, stop engine and remove PCV valve.
Shake valve and listen for the rattle of check needle inside
the valve. If valve does not the rattle, replace valve.
7) After checking, remove plug and install PCV valve.
8) Install air cleaner assembly securely.