BMW 530 insufficient coolant

Vehicle information: BMW 530LI 2019 model chassis G38
Engine model B48B20D displacement 2.0T
8AT automatic transmission
Fault analysis: The vehicle just replaced the mechanical cooling water pump two months ago
And replaced the auxiliary water pump
Now the owner reported that he added one liter of coolant every half a month
The vehicle was checked at the factory and it was indeed insufficient. The water level was at the bottom
Next step, according to the insufficient situation, analyze the common coolant leakage
Second, the water temperature is too high and the air pressure sprays the water out
First check that there is no water leakage in the replaced water pump
Second, the radiator water tank has no coolant leakage
Third, the heater water pipe has no leakage Fourth, the gearbox coolant radiator has no leakage
Next, you can use the water tank to pressurize and check the side leakage instrument
Finally, start the vehicle and keep the accelerator at 2500 rpm for 15 minutes
Leakage under the auxiliary water tank, replace the auxiliary water tank assembly to solve