Originally Posted by Zybane
Curious to know how the car senses a PCV problem, pressure?
Pressure seems likely, because the line is putatively at higher pressure than ambient (other candidates such as temperature and O2 content wouldn't be altered via a pressurized hose leak). Pressure is going to be lower at the intake with the can installed, that's basic fluid dynamics. However, given the size/design of the ProVent, the pressure drop seems like it would be minimal.
If there is enough slack in your hoses, you could temporarily take the ProVent out of the PCV circuit (leaving it mounted in the compartment) and check the existing hose run by connecting it together without the ProVent to see if it still throws codes. If the problem persists, that suggests a hose problem. If it doesn't...