4M0 121 550 D · Coolant hose Audi genuine (OEM) part number 4M0 121 550 D, Coolant hose. Fitted on (3)HOSE — pos 12 (KAT429.BIN)HOSE — pos 12 (KAT859.BIN)HOSE — pos 25 (KAT859.BIN) Open the interactive exploded diagram →