Genuine OEM Audi Reduction Agent Supply Line, part number 5Q0131984Q. This critical component is responsible for safely transporting the reduction agent, commonly known as Diesel Exhaust Fluid (DEF), from the supply unit to the exhaust system. It plays a vital role in the Selective Catalytic Reduction (SCR) system, which reduces harmful nitrogen oxide emissions. The line is designed to withstand the specific chemical properties of DEF and the operating temperatures of the exhaust system. Weighing approximately 0.225 kg, this line ensures reliable fluid delivery. Choosing a genuine OEM supply line guarantees the correct routing geometry, material compatibility, and resistance to corrosion, preventing leaks and ensuring the proper function of the vehicle's emissions control system.