When the water separator in the is filled with coolant, the coolant expansion tank must be extracted:

WARNING: This page is about a different car, the 2023 Volkswagen Atlas. However, it is still accessible from the selected car via links, so may be relevant.

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-- Close the shut-off valve -B- and switch off the Electric Vacuum Pump.

-- Seal the supply hose -2- and the return hose -1- of the coolant expansion tank using the Hose Clamps - Up To 25mm:3094 .

-- Remove the connector coupling -arrow- and open the shut-off valve -B- the coolant expansion tank is vented with this.

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-- Remove the Cooling System Charge Kit:VAS 6096 and Cooling System Tester - Directional Valve:VAS 691 005/5 .

-- Extract the coolant from the coolant expansion tank.

-- Reinstall the Cooling System Charge Kit:VAS 6096 and Cooling System Tester - Directional Valve:VAS 691 005/5 and remove the Hose Clamps - Up To 25mm:3094 .

-- Switch on the Electric Vacuum Pump and extract again for five minutes.