Genuine OEM Audi Vacuum Check Valve, part number 058905291B. This small but critical component regulates vacuum flow within various engine systems, ensuring that vacuum pressure is maintained in one direction and preventing backflow. It plays a key role in the proper operation of components such as the brake booster, emissions control, or fuel system. Using a genuine OEM check valve guarantees precise opening and closing pressures, durable materials, and reliable sealing, which are vital for maintaining engine efficiency and preventing vacuum leaks.