Genuine OEM Lexus V-Ribbed Belt Tensioner, part number 1662031090. This tensioner maintains proper tension on the V-ribbed belt, ensuring reliable operation of accessory components like the alternator and power steering pump. It is typically mounted near the belt pulleys and uses spring tension to compensate for belt wear. Genuine OEM tensioners are designed with precise spring force and durable materials for consistent performance and long service life.