The purpose of the Volkswagen fuel filter is to remove any particulates that might be present in the fuel so the other fuel system components on your engine will not be negatively affected by their presence. The necessity for clean fuel has increased with the use of the fuel injection system now on all Volkswagen vehicles. Fine particulates are being removed by the fuel filter so the fuel injectors can remain as clean as possible and their nozzles at the ends will be able to produce a uniform atomized spray for an extended period of time. Unlike the oil filter that has a bypass valve, the Volkswagen fuel filter does not. Once the fuel filter reaches its saturation limit of particulates, the flow of fuel through it will begin to diminish. This will hinder the performance and mileage of your Volkswagen engine. The replacement of the fuel filter on your vehicle should be scheduled during a routine tune-up. For most drivers that seek to take exceptional care of their car or SUV this is an annual event. If this is not part of the periodical maintenance schedule for your vehicle, it should be placed on it immediately. It is the only way to ensure enough fuel is reaching each of the cylinders so the engine can operate as it was designed to do. The location of the fuel filter on a Volkswagen differs from model to model. One thing is for certain: it is located between the fuel tank and the intake port of the fuel injection system. If you are unsure of its location a service manual for your model can be purchased showing its exact location so its replacement can occur at the owner's discretion.