E90 Auxillary water pump

[Bossman]

Took my 330D for routine oil service last week and the technician let me know that there is a fault code about the aux water pump in the memory, apparently its used with the heat exchanger for heating in the car.
I asked him to pull it off for me as the car is at BMW anyway for servicing.
at my workshop I checked it with the bench power supply, sure enough it did not start.
I pulled it apart, cleaned it and after testing took it back for them to install again.
Saved a couple there I reckon!
Also changed the coolant as well!

 

[Hellas]

Good thing they have the aux pump since most cars have their heat exchanger directly on the same water system as the engine, hence when something goes wrong on that side of the plumbing unnoticed, you have a seized engine...