Genuine OEM Volkswagen Engine Timing Chain Tensioner, part number 06M109218J. This critical engine component is responsible for maintaining the correct tension on the engine timing chain, ensuring precise synchronization of the crankshaft and camshafts. It is typically located on the right side of the engine's timing assembly. Constructed from durable cast metal, it often incorporates a hydraulic or spring-loaded mechanism to automatically adjust tension. Installing a genuine OEM timing chain tensioner is crucial for preventing timing chain slack, which can lead to engine damage, and ensures the exact factory-specified tension for reliable engine performance and longevity.