This Bosch original equipment leak detection pump is part of the evaporative emission control system. The purge valve helps prevent fuel vapor from escaping into the atmosphere by metering the flow of vapor from the active Charcoal filter to the engine in accordance with the engines operating state. The leak detection pump continuously checks for leaks in the EVAP system to ensure it is functioning properly. You can install Bosch leak detection pumps with complete confidence knowing that they are of the highest quality and meet or exceed OE specifications in fit, form, and function.