Part number for S3 rear differential?

Rip

Registered User
Can anyone please tell me what part number the rear differential assembly is on a 2014 S3? I'm assuming there might be several compatible part numbers including maybe VW?

Mine has started whining at about 40mph and more so while coasting and it's annoying me now. As there doesn't seem to be any fix for it I'm going to have to gamble on a 2nd hand one and hope it's quiet.
 

pburv

Registered User
Can anyone please tell me what part number the rear differential assembly is on a 2014 S3? I'm assuming there might be several compatible part numbers including maybe VW?

Mine has started whining at about 40mph and more so while coasting and it's annoying me now. As there doesn't seem to be any fix for it I'm going to have to gamble on a 2nd hand one and hope it's quiet.
Part number- Rear Diff main unit: OCQ525010K
Part number- Rear Diff ECU : OCQ907554H


Got this off a salvager's site on ebay. So not sure if 100% correct.
 

Rip

Registered User

Rip

Registered User
I've had my oils done recently and the diff did have oil in it.
 

Rip

Registered User
Part number- Rear Diff main unit: OCQ525010K
Part number- Rear Diff ECU : OCQ907554H


Got this off a salvager's site on ebay. So not sure if 100% correct.

I'm assuming I wouldn't need another diff ECU as my current one should be fine.
 

HertS3

Registered User
I'm the author of the above post - I know all about rear diffs! Mine is a late 2014 build (car delivered early 15) and I had the F variant on my car. You can get any 0CQ525010X where X is what you have or later; there were D, E, F, H, K, J, L and S I believe (S is the current version you get new from Audi if you fork out £3,800!!!)

There are a few knocking about on eBay, what I would say is play the waiting game, not many of these sell, if you watch the items or message sellers they'll give you big discounts on the prices they ask on their listing. If you look at the thread above, I found one guy that was willing to sell for around £200. I'd be weary of West Yorkshire-based dealers, the one I got was from a Nottingham breaker and (touch wood) all fine so far
 

HertS3

Registered User
Oh and you can keep the existing Haldex ECU, I did, otherwise you need to programme the new one to your car
 

Rip

Registered User
I'm the author of the above post - I know all about rear diffs! Mine is a late 2014 build (car delivered early 15) and I had the F variant on my car. You can get any 0CQ525010X where X is what you have or later; there were D, E, F, H, K, J, L and S I believe (S is the current version you get new from Audi if you fork out £3,800!!!)

There are a few knocking about on eBay, what I would say is play the waiting game, not many of these sell, if you watch the items or message sellers they'll give you big discounts on the prices they ask on their listing. If you look at the thread above, I found one guy that was willing to sell for around £200. I'd be weary of West Yorkshire-based dealers, the one I got was from a Nottingham breaker and (touch wood) all fine so far

Legend, thank you, that's literally all I need to know then!
 

Rip

Registered User
Oh and you can keep the existing Haldex ECU, I did, otherwise you need to programme the new one to your car

Do you mind if I PM you if I have any queries before I buy one?
 

Rip

Registered User
Sure, no problem

Nice one. The electrical wire going in to my diff is all knackered (dry and flakey), is that the ECU wire?
 

HertS3

Registered User
Not sure about that, better asking a mechanic, but I would imagine that it is the electrics/comms for ECU
 

Rip

Registered User
Thinking about it, new/used diff will have its own wire anyway regardless of what it is.
 

HertS3

Registered User
To me it's a no-brainer, you can pick up a used one (some with low mileage) for around £200 or a new one for £3,800. Problem is if you have a problem with it, extended warranty (if you have it, I do) will probably not pick it up, then again you could just buy another one.

After my experience with the original rear diff I would say definitely get a mechanic to check the diff oil when you're servicing your car, my one seems to have gunked up for some reason which caused its eventual demise. Could be a design flaw, though I've not seen swathes of people complain about it so may only happen to several unlucky ones among us.
 

Rip

Registered User
To me it's a no-brainer, you can pick up a used one (some with low mileage) for around £200 or a new one for £3,800. Problem is if you have a problem with it, extended warranty (if you have it, I do) will probably not pick it up, then again you could just buy another one.

After my experience with the original rear diff I would say definitely get a mechanic to check the diff oil when you're servicing your car, my one seems to have gunked up for some reason which caused its eventual demise. Could be a design flaw, though I've not seen swathes of people complain about it so may only happen to several unlucky onesamong us.

I didn't buy the car new so I guess warranty is out of the question. For the cost of a used one I'll gamble it. Hopefully the fitting cost won't be too much, not sure exactly what's involved to be honest, shouldn't be 'too' much work.
 

HertS3

Registered User
Yeah I bought mine at 3.5 years old too. I got an L rear diff for £370, but like I said can get it cheaper, look at the previous thread, that part was going very cheap from a low mileage car, may well still be for sale!

I think it's an hour or two of labour, plug n play really (if keeping Haldex ECU), you'll need to get new Haldex and rear diff oils for it as it'll come drained, so those will set you back probably around £70.
 

Rip

Registered User
I've made them an offer so hopefully I'll end up with it after some negotiation.
 

HertS3

Registered User
I've made them an offer so hopefully I'll end up with it after some negotiation.
Best of luck. Just check with them the variant, what car it came off and its mileage, I seem to recall it was a low mileage one and I think variant L which is pretty much as new as you're gonna get used (S is most likely from the new WLTP cars, doubt there's many around that have been written off already).
 

Rip

Registered User
https://www.ebay.co.uk/itm/401862831315?ul_noapp=true this is the one that I should've got, you should be able to haggle with him to get the price down more :rockwoot:

Best of luck. Just check with them the variant, what car it came off and its mileage, I seem to recall it was a low mileage one and I think variant L which is pretty much as new as you're gonna get used (S is most likely from the new WLTP cars, doubt there's many around that have been written off already).

It's an L yes and under 10k miles. Thanks for the lead on that!
 

HertS3

Registered User
It's an L yes and under 10k miles. Thanks for the lead on that!
That's the best of the bunch, the one I got was similar but slightly higher mileage. You're welcome :)
 

Rip

Registered User
Well hopefully I'll get it.
 

HertS3

Registered User
I'm sure you will, just a question of how much. He said to me at the time (it was advertised for £399) that he'd do it for £300 delivered, he'll probably take less as time ticks on!
 

Rip

Registered User
My offer isn't far away from that so fingers crossed, I'll negotiate when he gets back to me.
 

Rip

Registered User
Here's a video of someone replacing their diff on a Mk7 Golf R. Without using a car lift!

That actually doesn't look to bad.
 

Rip

Registered User
Would be easier if you had access to a lift, but as you said not too difficult.

Well going by that video getting someone else to fit it on a ramp shouldn't cost too much. Luckily I know the owner of a reputable VW/Audi tuner who I trust and charges fair prices so all should be ok.
 

pburv

Registered User
Well going by that video getting someone else to fit it on a ramp shouldn't cost too much. Luckily I know the owner of a reputable VW/Audi tuner who I trust and charges fair prices so all should be ok.
If it was me personally I would get a garage to do it. Only for the fact they have lifts . but if you had no option then doing it yourself is doable.
 
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Rip

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I'm sure you will, just a question of how much. He said to me at the time (it was advertised for £399) that he'd do it for £300 delivered, he'll probably take less as time ticks on!

Got it for £290 delivered, I'm happy with that :)
 

HertS3

Registered User
That's a result! Mine was £370 delivered so you got a very good deal indeed
 

Rip

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oyvind_norway

New Member
I'm the author of the above post - I know all about rear diffs! Mine is a late 2014 build (car delivered early 15) and I had the F variant on my car. You can get any 0CQ525010X where X is what you have or later; there were D, E, F, H, K, J, L and S I believe (S is the current version you get new from Audi if you fork out £3,800!!!)

There are a few knocking about on eBay, what I would say is play the waiting game, not many of these sell, if you watch the items or message sellers they'll give you big discounts on the prices they ask on their listing. If you look at the thread above, I found one guy that was willing to sell for around £200. I'd be weary of West Yorkshire-based dealers, the one I got was from a Nottingham breaker and (touch wood) all fine so far

Found this post and I just have to Ask: I have an 0CQ 525 010D, can I use the 0CQ 525 010 F without any problems?
 

oyvind_norway

New Member
I'm the author of the above post - I know all about rear diffs! Mine is a late 2014 build (car delivered early 15) and I had the F variant on my car. You can get any 0CQ525010X where X is what you have or later; there were D, E, F, H, K, J, L and S I believe (S is the current version you get new from Audi if you fork out £3,800!!!)

There are a few knocking about on eBay, what I would say is play the waiting game, not many of these sell, if you watch the items or message sellers they'll give you big discounts on the prices they ask on their listing. If you look at the thread above, I found one guy that was willing to sell for around £200. I'd be weary of West Yorkshire-based dealers, the one I got was from a Nottingham breaker and (touch wood) all fine so far

I just found this thread and I just have to ask:
I have 0CQ 525 010D, can I use 0CQ 525 010 F without any problem?
 

HertS3

Registered User
Answer is yes
 

HertS3

Registered User
I went from D to L, you can keep the existing Haldex ECU to avoid having to programme the new one, it's just plug and play that way. What happened to your rear diff? Your oil disappeared like mine?
 
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