Where is Auxiliary water pump located E60 550i
 

Anyone is familiar with this pump location, how hard it is to replace?
I'm getting error code 009C6B and most likely this is the part to be replaced.

I don't think the 550 has a auxiliary water pump. There are a few differences from the 545 so check into it. Go to realOEM and see if you can find it.

Thanks for your replies.
I can confirm for '08 550i does have auxiliary water pump, item #7 (part number 64116988960):
RealOEM.com - Online BMW Parts Catalog

Ordered it and expecting delivery this week.
Will be DIY, it does not appear to be complicated, removing the airbox and the challenging part will be to have minimum coolant spill during hose connection transfer from old to new.

Ax water pump
 

Replacement completed during the weekend, picture shows the new aux water pump installed, ready to mount back the airbox.
https://i.postimg.cc/SRXyV9ML/awp1.png

Great job! For once there is an easy repair for the N62 V8! There's not many.

By the way, is any coolant bleeding required for E60 550i or they self bleed on the go?
I had minimum coolant loss during this process, approx 1 cup, that is how much I added after to make the normal mark.

I've always used this procedure.Before refilling coolant:
Turn key to on but do not start engine
Set temperature controls to full warm
Set blower control to low
Set seat heater controls to maximum
(Auxillary pump should be running now)

Fill coolant through expansion tank to max position
Start engine and run at idle speed for one minute with expansion tank cap removed
Adjust coolant level to max and then replace expansion tank cap
Continue running engine until full operating temperature.
Turn off engine and let cool completely.

Remove cap once fully cooled and top off expansion tank to max level.