Cooling system cannot be bled properly on vehicles with an electrically/pneumatically controlled water pump

Examples: Audi / Seat / Skoda / VW 1.4l, 1.6l, 2.0l TDI – CT1168WP1


Noise or temperature problems as a result of incorrectly bled cooling system. There is still air in the system following replacement of the electrically/pneumatically controlled water pump.


On vehicles with an electrically/pneumatically controlled water pump, the cooling system must be bled after being refilled using our vacuum filling device (Tool Box W01) and an additional diagnostic device with the necessary functionality. The reason for this is the thermal management system, which has additional valves that supply different heating circuits. The valves need to be opened for bleeding so that all heating circuits can be opened and bled. The various circuits are distinguished as follows: –

– Micro-circuit = cooler for exhaust gas recirculation, heat exchanger for heater and heater support pump

– High-temperature circuit = coolant regulator, radiator for coolant and coolant pump

– Low-temperature circuit = charge air cooler, charge air cooling pump and cooler for charge air cooling circuit


It is essential to follow the vehicle manufacturer’s instructions and information when carrying out repair or maintenance work on the cooling system. The cooling system must always be bled with the help of a vehicle diagnostic tester using its “guided” function.

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Published on: August 30, 2022

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