Genuine OEM Volkswagen Cylinder Head Non-Return Valve, part number 03C103175G. This small but vital component is designed to prevent the backflow of fluids within the cylinder head system, maintaining proper pressure and flow direction. It is typically located within the cylinder head assembly. Constructed from durable black plastic, this valve measures approximately 0.138m in length. Choosing a genuine OEM non-return valve ensures accurate fluid control and long-term reliability for critical engine systems.