Genuine OEM Audi Belt Tensioner, part number 04L903315A. This essential component is responsible for maintaining the correct tension on the engine's accessory drive belt, ensuring the efficient and reliable operation of systems like the alternator, power steering pump, and air conditioning compressor. It is positioned within the engine's accessory drive system. Weighing 0.616 kg, this tensioner is engineered for durability and precise function. Opting for a genuine OEM belt tensioner guarantees factory-specified spring rates and pulley alignment, preventing premature belt wear, slippage, and potential damage to engine accessories.