Where is my PCV valve located on my 1999 Honda CR-V?

The valve itself (a cylindrical object clamped into the rubber hose at both ends), is located in a hose that leads from the valve cover and runs to the fuel rail. Look for such a hose and follow it towards the fuel rail. It is replaceable with a part readily available at any auto supply store.

(Hint: they can also be cleaned, if not too deteriorated, by soaking them in carburetor cleaner or by blowing carb cleaner through them from an aerosol can until the spray runs clear.)

The theory is that the intake of fuel mixture will suck any fumes from the valve cover area and recirculate them into the combustion chamber to be burned.