Sports differential fault please contact workshop

[jayjam786]

Good afternoon

My B9 RS4 has been with Audi to have my panroof service upon collection and driving home I got this warning so turned car off and it disappeared turned back on again and it intermittently appears and disappears . Rang audi who said to bring it in. Any idea what it could be before I take it back


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[Jools]

The sport differential uses a small dc electric motor to control two valves which alter the pressure on the two clutches between the output from the differential and the drive shafts to the wheels, it could be anything from low diff oil to an elctrical control fault and everything in between.
There is no real way without either a VAG-COM or ODIS scan to tell what is reporting the fault.

Either way if Audi are going to do it and you're out of warranty get ready to loosen your belt and drop your trousers!
They are nearly £7k new, there some one on eBay at the moment for considerably less.

Best of luck

[jayjam786]

Thankfully the car has extended warranty just found it bizarre that it occurred whilst it has been in the workshop. Must have been sending it around some serious bends whilst in their possession or maybe just a coincidence but thanks for the insight.


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[E10EAN]

Mine does this when I forget to turn the ghost off and resets once restarted.

[jayjam786]

Interesting you say that because I had the wiring harness changed for my keyless entry on driver side door handle as it had corroded so it could potentially be an electrical issue


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[Jools]

Talking of the Ghost Alarm, apparently some types of Can-Bus alarms secure the car by 'crashing' the Can-Bus communication if they are not deactivated, which causes the car elecronics to shut down, so stopping the engine / theft.

It would be interesting to compare a pre and post car scan of it being started without deactivating this type of alarm to see what errors are reported.

[linq]

Interesting discussion. When I bought by B9.5 last year, it already had a MetaTrak tracker fitted. A few months ago, I had the tracker upgraded with an immobiliser and, since then, I occasionally get two or three warning messages popup when I turn on the ignition. It only happens once in around twenty starts but one of the messages that usually appears is 'Sports differential fault'.

[Jools]

The plot thickens!
Ling. Does the sport differnetial fault on the dash then clear after the start or on the next start stop cycle? It would be nice to have a scan when it happens.

Me thinks crashing the CAN-Bus is one of those 'sounds like a good idea' at the time things that can actually cause 'Ghost' faults sometimes later on.

[linq]

When the ghost warning messages appear, the car starts and drives fine (with the last warning message continuing to be displayed). In practice, what I normally to do is turn off the ignition, wait a few seconds, turn it on again and the car invariably starts OK with no messages.

As it happens, I did get an OBDeleven dongle last week - I haven't got around to using it yet but I'll try and get a scan once I've set it up.

[Jools]

Look forward to your results, it might be interesting.

[linq]

@Jools, I've setup my OBDeleven. When you refer above to a pre and post scan, do you just mean running a 'full scan' before and after starting the car or are you referring to capturing the live data for a specific control module?

[Jools]

linq
A standard scan before and after should be enough.
As I've never had need to look at live data before on that module I don't know what's available and what would be best to look at.
Honestly I don't know which module the diff fault is recorded to. Audi never seem to put it where you would expect it to be.
I would be guessing at, address 32 differential locks (J187).
Having read a couple of other threads the actuators seem to be favourites. The fix reports seem to suggest they might stick and not seal fully causing the oil pressure to be too low and reporting a fault.
It looks like there expected standby pressure is +40bar, a faulty actuator I assume when it is stuck open is about 1.5bar.
Only reading into the other stuff I've read.