The Genuine Volvo Fuel Pressure Sensor and Rail Assembly - 31478556 is a high-quality component designed for use in Volvo vehicles. It is responsible for measuring the fuel pressure in the engine's fuel rail and relaying that information to the vehicle's engine control unit. This allows for precise fuel delivery and efficient engine performance. The assembly includes the fuel pressure sensor and the fuel rail, making it a complete and convenient solution for maintaining the fuel system of a Volvo vehicle. It is a genuine Volvo product, ensuring reliability and compatibility with the vehicle's systems.