Expansion tank cap | 025 121 321B

Expansion tank cap | 025 121 321B

The cap of your expansion tank might look simple, but it ensures the correct pressure in your cooling circuit. This original Volkswagen cap (OEM 025 121 321B) universally fits standard expansion tanks and keeps your cooling system at the right temperature. Regularly check this cap for wear or deformed sealing rubber, as a poor seal leads to coolant loss. Combine this cap with a new expansion tank or heater hose set for a fully functioning cooling system.