This morning I changed the diff fluid, replacing fill and drain plugs. Straightforward, if a little time consuming on axle stands.
I did it myself as I wanted to see the state of the fluid to guage the condition of the diff. The fluid was mid brown, rather than really dark, in compareison to the golden hue of the new haldex fluid, so all good!
I presume were talking the VAQ diff fluid.
Did you drop the pump out and clean the gauze filter, was it made up with crap??
Did you do the pump adaptation after refilling??
I can't seem to find out for definite if the adaptation is really needed after doing a diff service.
I researched replacing the fluid in some detail, it seems you can potentially cause issues removing the pump and filter?
My car has only done 10k miles. so this would be it's first diff fluid service.
I used the OBDeleven for live data on the diff for temperature and it also shows; "Haldex clutch status! & "degree of blockage".
As the temperature. status & degree of blockage (0%) were all great with 0 minutes of overtemperature recorded, I decided to drain and consider the status of the fluid coming out.
As I mentioned the fluid looked clear only a slightly darker colour than the new Febi Bilstein fluid that replaced it.
On that basis to avoid any complication, I did not remove the pump, just blew it out with compressed air and replaced the fluid, which is exactly what the VW main dealer did on the diff service on my previous GTi PP.
Now
if the old fluid had looked like a diesel oil, I had considered this may well be down to wear on the diff plates, I would have looked into removing the pump and inspecting the filter.
As all of my readings and fluid looked fine, I had no need to recallibrate anything. I ran the car up the road to see the diff temperature increase and watched the live data as I went through a few turns, all good.
I would consider the mileage on your own car, how often the diff fluid has been replaced and what it looks llike when it comes out?
This is why I wanted to do this change myself as I wouldn't get the information I learned about the car from a secondhand source.
Good luck!