BMW Check Valve for Brake Booster Hose - 34331151533

ATE BMW Check Valve 34331151533 is an OEM-style check valve (one-way “non-return” valve) designed for the brake booster vacuum hose on various classic BMW models. It allows vacuum pressure from the intake manifold to flow into the brake booster while preventing it from flowing back, helping ensure consistent brake assist performance and a firm pedal feel. This simple but critical vacuum-system part helps maintain proper brake function by preserving booster vacuum when the engine load changes.