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Discussion Starter · #1 · (Edited)
Hi all,

Sorry for the "Help Me" post, but please, Help Me!.

Car in question is a Golf MK 7.5 Se Nav 2.0 TDI S-A DSG (2017)

Short story is, my car went in for a service and at the same time said it needed a software update. Collected the car and within an hour the car flashes: Gearbox Fault - Okay to drive on. Goes back to the dealership today and I'm told "£600 for a new aux pump in the DSG".

Software update: 23X4
Error code: P0C2900
Notes from the engineer attached (they are hard to read but basically say everything looks fine but wanna try swapping the aux motor - which they expect I will foot the bill for).

Fine before the update afterwards the car is chugging down the fuel before throwing up an error that neither my brother nor I can clear.

All sounds very dodgy... either the fault is software driven, the new software is detecting a fault the old software couldn't or the car randomly decided to develop the fault immediately after the service.
 

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The pump is not an easy part to replace. Cars can fail at any point and just because the car is with a garage (main dealer or otherwise) if it goes wrong when in someone else’s charge, it is not necessarily their fault… it could be but not by any way provable. Failure of the DQ200 system pump accumulator is VERY common and can happen at any point.
 

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I have literally had the same issue after the software upgrade!!!!

We have the same exact car and same exact error that I cannot clear!!!

Did you try and solve this by downgrading to the original software??

Thank you so much
 

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Hi all,
I have golf MK7.5, 2.0 TDI, DSG DQ381
I faced the same error after the software update: 23X4, increased fuel consumption and got the same error.
Has someone been able to solve this problem?
Thank you
 

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Hi all,
I have golf MK7.5, 2.0 TDI, DSG DQ381
I faced the same error after the software update: 23X4, increased fuel consumption and got the same error.
Has someone been able to solve this problem?
Thank you
Yes. Volgswagen will be unhelpful. I am 100% sure that it's a software issue. Not mechanical!! Where are you based? I got someone to get a software downgrade!
 

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Yes. Volgswagen will be unhelpful. I am 100% sure that it's a software issue. Not mechanical!! Where are you based? I got someone to get a software downgrade!
I'm in Germany... Volkswagen kept car at the service one week and did nothing...
Definitely not mechanical, I did test hydraulic pump over vcds and it works, pumps 11bar.
Do you know which sw was before 23x4 upgrade? Did you do software downgrade?
 

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I'm in Germany... Volkswagen kept car at the service one week and did nothing...
Definitely not mechanical, I did test hydraulic pump over vcds and it works, pumps 11bar.
Do you know which sw was before 23x4 upgrade? Did you do software downgrade?
Yes I did software downgrade. They update two softwares. The one for the ECU and one for the TCU (for the DSG) that's the one that gives issues.

I downgraded the ECU one first and nothing changed. Then the TCU one and the car went back to what it was.

ECU one that they put is 7728 and the older one was 4026.

The TCU one I am not sure but all you need is Autotuner and they have it saved on the cloud (just downgrade of one version). You can do everything from the OBD port if you have autotuner or anyone else that you know.

Ask VW and tell them to write down the previous files they have them saved.

Do not allow them to do any work on the car because the guy above had the whole system replaced and nothing changed.

If anyone else reading this forum has the same issue, please comment below and let's contact VW. It's 100% a software issue!

Also it might void your warranty if you downgrade the software. But better than having that warning light forever with no fix.
 

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I have also had the same problem as above on my 2017 Golf GTD.

Software update: 23X4
Error code: P0C2900

Car went into VW for a service and at the same time they did the apparent control unit recall (software update 23X4). Collected the car and before I even left the car park it flashes up Gearbox Fault - Okay to drive on.
Now they are trying to claim it is a fault in the AUX pump in the DSG. The car was perfectly fine when I dropped it off at the dealership and I’ve never had any previous issues with it. All of a sudden before even leaving the dealership it is now an apparent issue.

It is quite clear that this is software related since multiple people are having the same issue after the 23X4 software update. Now to have the argument with VW when I request for the software to be restored to it’s previous version. Quite unbelievable that these “software updates” are released to the public which seem to do more harm than good.

Interested to hear anyone else’s experience regarding this?
 

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When people come in and ask me about software updates they have read about ont tinterweb I ask “why, is there an issue” and usually the answer is no and so I say it is not work the risk, if I did it and something went wrong or even a random simultaneous failure (it happens) then I am left responsible, if it ain’t broke, don’t fix it.
 

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Yes literally so many of us are having the same issue with the same car in many parts of the world.

I think we need to get in touch with VW because this is not acceptable.

We need a compensation or something because there is clearly an issue on the software that needs to be addressed ASAP.
 

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When people come in and ask me about software updates they have read about ont tinterweb I ask "why, is there an issue" and usually the answer is no and so I say it is not work the risk, if I did it and something went wrong or even a random simultaneous failure (it happens) then I am left responsible, if it ain't broke, don't fix it.
Unfortunately they force on doing it because it will say the car won't be under warranty anymore. You have no choice sometimes..
 

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Don’t be so eager for compensation, it puts peoples backs up. You do have a choice, go to an independent specialist who cares, by law this cannot impact on your warranty as long as the correct parts and procedures are used; the only possible downside is in the event of a failure just outside warranty where they can legally tell you to go do one.
 

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hi guys glad I found this . Basically my car a 2018 gtd dsg went to have a body repair at a VW body shop whilst it was there it went into there garage as well don’t know why I only know this as my dash cam showed footage . Anyway I picked the car up everything was fine fast forward three weeks and it’s just popped up “ error gearbox you can drive on “. Got a mate to read the code before it goes in to VW tomorrow
P0C2900. Anybody think this could because they updated software whilst in garage
 

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13256(P0C29)- Activation of extra hydraulic pump for gearbox oil - unreasonable, intermittent error - Not confirmed - Tested after memory cleared

The only way to know is to have the box scanned and look at the update history.
 

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SOLVED

Following on from my previous post. The solution to the gearbox fault caused by the 23X4 software update is to reverse the TCU software back to the previous version.

After the 23X4 software update was carried out by VW the software versions on my vehicle were:

ECU - 7728
TCU - 1637

Reversing the TCU software back to the previous version, which is version 1431 removes the gearbox fault. This returns the vehicle back to the condition it was in before the 23X4 update. I did not change the ECU software, only reversing the TCU software is required.

My advice to anyone reading this who is experiencing the same problem after having the 23X4 update carried out by VW is to not listen to them and not let them touch your vehicle. Certainly do not let them replace the AUX pump. Find a tuning garage local to you that has the ability to reverse the TCU software.

After nearly two weeks of arguing with VW, they would not listen to me and their "technical department" insisted that the software could NOT be reversed and the AUX pump would need to be replaced. This is complete rubbish, of course the software can be reversed. I took my vehicle to a third-party garage who reversed the TCU software back to the previous VW version in less than 10 minutes, problem solved. VW do not want to take responsibility for the problems caused by the 23X4 update and will insist it is not the software that is causing any issues.

For anyone in the UK you can raise a complaint to the VW customer service team, the number is 0800 083 3914. Once you have raised the complaint you need to request to escalate it to the executive office. This bumps the complaint up to the head office and a case handler will be assigned. The more people that highlight this issue to VW the better.
 

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To be fair mate my car was out of warranty at 35000 miles on an 18 plate . 23x4 was installed on my car by very when it was in a VW body shop. I had the car back three weeks before the fault showed . I put it back to VW. To diagnose they said it was the update that caused the issue in relation to ware parameters that were not met that the software expected to see we’re not met throwing the code up . This what I was told by the master tech . They replaced the aux pump even though he said the original pump was fine . I asked them if the pump was still working whilst the code was active to which he couldn’t say yes or no . Which in turn worried me as to temperatures in the box without the extra cooling of the aux pump . I never had a warning of overheating and drove minimally before bringing it to be seen . It was all covered by VW and he said he had also done three other golfs under warranty out of warranty. Mines now fine again
 

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Hello everyone, the problem was solved by replacing the gearbox with a new one, before that an auxiliary pump was replaced, but this did not help solve the problem. Then there was noise from the transmission. I returned the car to the service, they said I need to change the gearbox (car mileage is 115,000 km). Replaced with a new gear box one. Drove 100 km the error did not recur
 

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Well this is interesting. 23X4 was carried out whilst my 2018 2.0TDi DSG was in for service a few weeks ago. Why? The car has been faultless for 4 years. I'm guessing VW is trying (again!) to make retrospective improvements to emissions.

I've not had the gearbox fault and error message that others have seen, but it was immediately obvious that the gearbox behaviour was completely different. I've always used the gearbox in S mode and it now behaves as though S mode has been deleted, and S has become D, or super economy D. It's now changing up much earlier and holding onto gears longer on the way down. Engine braking is now almost non-existent. 30mph in town has always been in 3, now it's in 5 with revs just a fraction over 1000rpm. And it feels reluctant/slow to kick down. Needless to say, I hate it and want it put back to factory settings. I also have a suspicion that fuel consumption is higher (you might expect the opposite), but it's hard to prove it.

I contacted VW Customer Services, who bounced it back to the dealership 2 weeks ago. The dealership hasn't yet bothered to contact me. I'm not optimistic that I'll get anywhere when/if they do. The take home message from posts above is that I'm going to need to find a VW independent who can reverse the TCU software version. Does anyone know what the ECU changes have done? Is it worth trying to get that reversed at the same time?
 
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