Problem with Haldex? S3

[gareth_oau]

i'd also suggest the oil. i think its around $150 for a small dribble thats needed.

If that fails, then buy replacement gear ex UK or US

[Rob Burns]

If you do get a Haldex oil and filter change (it is due every 60k) then make sure that whoever does it knows what they are doing. I know of more than one case where the person doing the job has drained the differential oil and topped up the Haldex oil. Car comes back on a tow truck with the diff pin seized and the front mount snapped off when the Haldex tried to engage.

[mk1turbo79]

Most common cause of those symptoms is the controller, get an APR one. Problems gone

[Manaz]

Most common cause of those symptoms is the controller, get an APR one. Problems gone

APR don't make one - they simply re-sell the Haldex one. And you can get them substantially cheaper than what APR sell them for if you know where to look...

For what it's worth, failing controller tends to result in no drive at the rear rather than binding up and noises...

[Kai_]

I came across this thread earlier today, might be related to your problem -
The Audi TT Forum :: View topic - Exploded rear differential

[Golf Loon]

Also worth checking the rear brake calipers and pads.
Had a couple of 4WD Audis recently with bent slider pins, which jamms the rear inner pad and confuses the traction control and abs systems.

I also have an S3 here for wrecking with a burnt interior, but complete running gear.