Not really proficient on the workings of a haldex but from reading on here the unit only comes into play for 4 wheel drive. On the basis that 99.9% of folk never go off road does the unit require servicing as frequently as is claimed by various enthusiasts.
Hopefully someone can offer an easy to understand answer.
edit : a supplementary question - if rear diff bearing has been replaced how does this effect, if at all, the haldex unit viz oil ? MY 09 GS manual in Lago Grey, Wood Co arm rest and side bumper strips - now sold.

MY 15 SD4 SE Auto Orkney Grey with colour coded Bumper Door Mouldings

The Haldex engages 4WD when you start the engine, presuming the car isn’t moving. As you move off and gain speed the Haldex disengages 4WD gradually in relation to speed until the car is in front wheel drive only. The Haldex stays live to re-engage 4WD if sensors decide that it is necessary. So stop start in traffic and the Haldex is in action as much as it might be crossing a grassy field.
On the oil question I’m less sure but if you’ve been working there to me it would be daft not to change it, but they are different fluids and I don’t think that taking off the differential loses Haldex fluid.

I have just had a diff from bell engineering and Austin said to do the oil and filter of the haldex at the same time, as it’s the only time to get to the filter for the haldex. I did not do the actual work myself it was done by local mechanic, I just assumed all the oil was lost when doing the diff.

as above did my diff a few weeks back and all the oil is lost when you swap over the haldex ideal time to do the filter and clean the pump filter + fresh haldex fluid . 2009 FL2 S now gone
2011 FL2 HSE AUTO
2012 FL2 XS AUTO
2000 Kawasaki er 5

Just a driver wrote:

I have just had a diff from bell engineering and Austin said to do the oil and filter of the haldex at the same time, as it’s the only time to get to the filter for the haldex. I did not do the actual work myself it was done by local mechanic, I just assumed all the oil was lost when doing the diff.

If it can’t be fixed with a squirt of WD40 I am out of my depth.😀

Bobupndown wrote:

Just a driver wrote:

I have just had a diff from bell engineering and Austin said to do the oil and filter of the haldex at the same time, as it’s the only time to get to the filter for the haldex. I did not do the actual work myself it was done by local mechanic, I just assumed all the oil was lost when doing the diff.

Not strictly accurate although sensible advice to do it now. The Generation 4 haldex had a large flange connecting the propshaft to diff. In order to remove the haldex pump to clean the pump screen the propshaft has to be removed, then the entire haldex separated from the diff in order to take this flange off to get the pump out. Sounds more complicated than it really is, I've done several haldex services this way. It can be done.

how do you remove the damper from the flange , as i was thinking of doing this would it just be as simple as cutting the rubber coupling between the flange and harmonic outer piece of metal ?  2009 FL2 S now gone
2011 FL2 HSE AUTO
2012 FL2 XS AUTO
2000 Kawasaki er 5

Unfortunately I didnt see how Austen @ Bell Engineering did it (I was cycling in the Wyre Forest) but he told me they made a tool to do it.
But I imagine they cut the rubber bewteen the two and maybe bivalved the damper to get it off without taking the prop off or just took the prop off.
You could contact him. Jules

Not all gen 4 Haldex units have the large flange. The Gen 4 on my 2009 MY doesn't. It's possible to remove the pump and drain the fluid with the propshaft and the Haldex still in the vehicle. Its not so easy to get to the filter cap bolts, but it's still possible to get to it.
This fluid change I didn't bother with the filter, as it had only done 5k miles since it was replaced.
I changed to fluid to see what effect it has on the shudder when cornering, which it's actually cured for the time being.

The Haldex connects the drive to the rear a lot more than many would realise, but the shudder mine was making showed it's connected an awful lot of the time. 2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ionic 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.

cheers jules thats someting to think about the next time i take it off .
nodge68 i think its the manual fl2 that dont have the large flange fitted as my 09 manual was easy to change but my wifes hse auto and my xs auto both have the large flange  2009 FL2 S now gone
2011 FL2 HSE AUTO
2012 FL2 XS AUTO
2000 Kawasaki er 5

Thank you BossBob 👍 MY 09 GS manual in Lago Grey, Wood Co arm rest and side bumper strips - now sold.

MY 15 SD4 SE Auto Orkney Grey with colour coded Bumper Door Mouldings

robblue wrote:

cheers jules thats someting to think about the next time i take it off .
nodge68 i think its the manual fl2 that dont have the large flange fitted as my 09 manual was easy to change but my wifes hse auto and my xs auto both have the large flange

There's a joke in there but I wont go near it.

IIRC there maybe at least 2 flange sizes: certainly a flange and a large flange (inc damper) depending upon age and model. Jules

 2009 FL2 S now gone
2011 FL2 HSE AUTO
2012 FL2 XS AUTO
2000 Kawasaki er 5

robblue wrote:

cheers jules thats someting to think about the next time i take it off .
nodge68 i think its the manual fl2 that dont have the large flange fitted as my 09 manual was easy to change but my wifes hse auto and my xs auto both have the large flange

Makes sense.
My Haldex is just beginning to shudder again 500 miles on from a fluid change, so it looks like I'll be doing another sooner rather than later, until I can sort the issue permanently.  2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ionic 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.