just to name a few. i got my dem-006 code on my xc90 and this is what i did.
razor blade open the bitch, there was crap all inside.oily crap, haldex fluid leaking in.
used water to clean it out, compressed air'd it and resealed it. took the pump apart and cleaned it and it was still no good. found on vw vortex that their haldex controllers are the same as ours. there are alot more of those floating around so they should go for $50-100 completer. you can use the pressure sensor out of them($100 volvo part dem-0007 code) and use the pump out of it too.