Very common check valve that fails on all Audi A4 and VW Passat 1.8T engines. This valve will cause a vacuum leak leading to idle problems and loss of boost under load. There are multiple valves throughout the engine using this same valve. VW/Audi part # 058905291K
Part # 058-905-291-K / 058905291 K / 058 905 291 K / 058905291K
Vaico Part # V10-2108
