When coolant expansion tank performance matters, the FEBI BILSTEIN 44531 delivers — built to the same dimensional and material standards as the original part it replaces. The part is built to the following specification: for OE number: 4F0 121 403 M, Weight [kg]: 0, 765 kg, Material: Plastic, Supplementary Article/Supplementary Info: 896, Number of connectors: Aluminium. Each dimension is checked against the OEM reference to ensure the component seats and functions correctly first time. Compatible with AUDI vehicles; use the vehicle selector above to confirm exact fitment for your make, model, and engine variant. Fitment data is sourced from TecDoc, the authoritative European parts catalogue. This part supersedes original equipment references: 003-026-001, 03973, 043019N, 06317 and 63 more. Matching these numbers confirms a like-for-like replacement with no loss of function. FEBI BILSTEIN is a recognised supplier of automotive replacement components to independent workshops and dealer networks across Europe. All parts are sourced from authorised distribution channels and carry full manufacturer traceability — you receive exactly the same component supplied to professional garages and dealer workshops. If fitment or specifications do not match your vehicle, our technical team can help identify the correct alternative — use the vehicle selector or contact us with your VIN for a guaranteed-fit recommendation. Replacing worn components on schedule preserves your vehicle's safety, reliability, and resale value — and aftermarket parts from established brands deliver OEM-equivalent performance at a fraction of the dealer price. Every part is dispatched from our UK warehouse with a 30-day money-back guarantee and free hassle-free returns.

febi bilstein, founded in 1844 in Ennepetal, Germany, is one of the oldest and most comprehensive automotive parts suppliers in the independent aftermarket. febi bilstein offers over 40,000 parts spanning steering, suspension, engine, braking, cooling, and electrical systems. Certified to IATF 16949 and supplying OE-quality components, febi bilstein products undergo rigorous testing to match original equipment performance. With nearly 180 years of German engineering tradition, febi bilstein is the go-to brand for reliable, competitively priced replacement parts.