The area to access the PCV valve is the valve cover, and before removing the PCV valve, unscrew the clamp using pliers on what holds the hose then pull the clamp off the hose. It is recommended always to replace the O-ring when the PCV valve is removed. Connect the hose back to the valve and while the engine is running at normal operating temperature and restore your finger over the end of the valve; there will be no vacuum, check the hose and valve to find out if they are plugged and replace any plugged or deteriorated hoses. While buying a new PCV valve, make sure that it fits your car's make and engine capacity and that the old and new valves are of the same type. I pointed out that installation proceeds in the opposite order to removal.