More than likely this is a purge valve issue. It is not an external leak but what happens is the purge gets stuck open and sets the code. The reason it cannot start is when the purge is open it is allowing fuel vapor into the engine basically it is putting too much fuel in and it cannot fire the engine.
Unfortunately, we don't have a Polo in our service manuals so I cannot get you specific data on this one but if it were me, I would replace the purge and go from there.
Let me know if you have questions. Thanks
Sunday, October 6th, 2019 AT 3:34 PM