In a written communication attributed to Volkswagen, the problem stems from the fact that the fuel injector pulse rate happens to occur at the same natural frequency as injector line number two. Over time, the line could fail. That’s especially true on certain lines manufactured with tube material that contains scratch marks from a grinding process. Volkswagen says that the inferior piece can’t stand up to the stress of the injector pulse rate.
They’re working with the NHSTA on issuing a recall for the 09-12 models.