Genuine OEM Volvo Carbon Filter Tank, part number 31261338. This tank is an integral part of the vehicle's evaporative emissions control system, designed to capture and store fuel vapors from the fuel tank, preventing them from escaping into the atmosphere. It then routes these vapors to the engine to be burned. Genuine OEM carbon filter tanks are built with specific adsorbent materials and housing integrity to effectively manage fuel vapors and meet emissions regulations.