Genuine OEM Audi Reduction Agent Supply Line, part number 3Q0131983L. This line is responsible for accurately delivering the reduction agent, such as AdBlue or Diesel Exhaust Fluid (DEF), from its reservoir to the vehicle's Selective Catalytic Reduction (SCR) emissions system. This process is vital for converting harmful nitrogen oxides into harmless nitrogen and water. The assembly consists of durable flexible hose and connectors, weighing 0.283 kg and measuring approximately 0.33m x 0.33m x 0.09m. Choosing a genuine OEM supply line ensures precise fluid delivery, leak-free connections, and resistance to the reduction agent, which are critical for maintaining emissions compliance and system functionality.