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I just took my 2017 7.5 Golf TDI to a Volkswagen dealer in Australia for a routine service. Despite asking them not to apply updates they applied an engine control unit update 23x4, and a gearbox control unit DQ381 update. Here is what I've noticed in my first 2 hours of driving:

1. From stationary to moving forward or reverse with no accelerator the car picks up a lot more speed (the RPM is higher). The stationary idle engine speed is the same as before the update. The car may feel ever so slightly faster 0-5km/h but greater brake pressure is required to stop.

2. Gears change up at slower speeds. 1st gear may hold to a slightly higher speed but 3,4,5,6, and most notably 7 engage at slower speeds. As a result the car feels a bit laggy and sluggish.

3. The gear box moves up a gear when slowing down or rolling down hills resulting in less effective engine braking. This along with point 1, I'm expecting greater brake wear.

4. The turbo doesn't seem to be as potent, there is extra lag and the car no longer feels "unstoppable" when asked for brisk acceleration. This is the most disappointing experience for me.

I guess I'll learn more as I drive further...
Agreed - basically the car feels more sluggish, is often labouring in the wrong gear (too high) and the gearbox behaviour is messed up. My suggestion is to find an independent VAG tuning specialist who can put it back to stock. I started by asking the VW dealer what software versions were on the car before they updated it. Both ECU and TCU were updated by 23X4 and both really need to be reversed.
 

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An update since 23x4 and a DQ381 update was applied. I've driven about 250km and probably not surprisingly I've got the dreaded "Error: gearbox. You can drive on." message.

I've never had any issues with the car or the gearbox in my first 5 years of driving the car. I was 5 minutes into my usual journey to work, heading down the highway, the car had just changed up to 7th and I had to slow down. Moving from about 100km/h to around 78km/h the car got the error when it was still in 7th gear.

I have no idea why VW has programmed the car to stay in 7th gear at such a slow speed!!! With the previous software it would always change back to 6th at 88km/h now it consistently changes back to 6th gear at 78km/h.

In addition to my previous post, my other observations to date:

1. The 3 driving profiles have been completely recalibrated. Effectively sport mode has been removed. (@Solbay has mentioned this)
Previously I would have ranked each profile as:
Eco = 2/10.....Normal = 5/10.....Sport = 10/10
Now I would rank the profiles as:
Eco = 1/10.....Normal = 3/10.....Sport = 5/10

2. I really notice the slow down in gear change speed and clutch engagement, changes are no where near as sharp. This is really noticeable in the now defunct and pointless Sport mode.

3. I have had a very light rotten egg smell come through the cabin on 2 occasions. I've never experienced this previously although it could be from other vehicles. This is something I will keep an eye on. During a DPF process is this expected?

4. Reported consumption is currently lower than I would usually find. This could be just in the car reporting but given VW have made the car so lethargic it would be expected. I would happy change my car back to the previous software for an extra $1 of fuel a week.

In summary, I used to love my car. It was really fuel efficient, and a fun lively car to drive. The driving experience is now sub standard and I have errors and warning on both the dash and centre screen.
 

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No use to you but I found a Polish chap who dealt with a VAG diagnostic system ODIS cock up for me and he is doing good business going around rolling back DQ200 software “improvements”!
 

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An update since 23x4 and a DQ381 update was applied. I've driven about 250km and probably not surprisingly I've got the dreaded "Error: gearbox. You can drive on." message.

I've never had any issues with the car or the gearbox in my first 5 years of driving the car. I was 5 minutes into my usual journey to work, heading down the highway, the car had just changed up to 7th and I had to slow down. Moving from about 100km/h to around 78km/h the car got the error when it was still in 7th gear.

I have no idea why VW has programmed the car to stay in 7th gear at such a slow speed!!! With the previous software it would always change back to 6th at 88km/h now it consistently changes back to 6th gear at 78km/h.

In addition to my previous post, my other observations to date:

1. The 3 driving profiles have been completely recalibrated. Effectively sport mode has been removed. (@Solbay has mentioned this)
Previously I would have ranked each profile as:
Eco = 2/10.....Normal = 5/10.....Sport = 10/10
Now I would rank the profiles as:
Eco = 1/10.....Normal = 3/10.....Sport = 5/10

2. I really notice the slow down in gear change speed and clutch engagement, changes are no where near as sharp. This is really noticeable in the now defunct and pointless Sport mode.

3. I have had a very light rotten egg smell come through the cabin on 2 occasions. I've never experienced this previously although it could be from other vehicles. This is something I will keep an eye on. During a DPF process is this expected?

4. Reported consumption is currently lower than I would usually find. This could be just in the car reporting but given VW have made the car so lethargic it would be expected. I would happy change my car back to the previous software for an extra $1 of fuel a week.

In summary, I used to love my car. It was really fuel efficient, and a fun lively car to drive. The driving experience is now sub standard and I have errors and warning on both the dash and centre screen.
Interesting that you mention a deterioration in the "quality" of the gearchange, as well as everything else. I also noticed that gearchanges were slower and not as sharp, with a slurred change especially from 1st to 2nd. The 23X4 update (which updates both the ECU and the DQ381 transmission control unit) is truly a disaster in terms of its impact on driving experience. To reiterate, VW dealers claim to be unable to reverse any software updates via their system (ODIS). VW Customer Service in the UK have been completely useless and unwilling to answer any technical questions whatsoever, including what 23X4 is supposed to achieve. The only option was to find a VAG tuning specialist with access to original software versions and the ability to reflash both ECU and TCU - at my expense of course.

From a customer's point of view, this is completely unacceptable and, obviously, I will never again have my Golf serviced by a VW dealership.
 

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Hey guys, Thought i'd share some of the information i've come across this far.

I'm a tuner based in Denmark, and recently purchased a 7.5R with DQ381.

I allways update to recent software made by VW, as they normally come with positive upgrades (there is some tombstones in between, which we know of.)
- And of course i did this aswell on ECU + TCU from revision 1402 to 1628, however i instantly achieved the famous P0C29 as you others.

For this car i had following revisions to choose from: 1401, 1402, 1403, 1420, 1421, 1422, 1423, 1424, 1425, 1626, 1627, 1628

I manually tried all revisions down from 1628, untill i got the latest software without the DTC. = 1425.

So my conclusion is that rev. 1626, 1627, 1628 contains changes, that registers this error.
 

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Hey guys, Thought i'd share some of the information i've come across this far.

I'm a tuner based in Denmark, and recently purchased a 7.5R with DQ381.

I allways update to recent software made by VW, as they normally come with positive upgrades (there is some tombstones in between, which we know of.)
- And of course i did this aswell on ECU + TCU from revision 1402 to 1628, however i instantly achieved the famous P0C29 as you others.

For this car i had following revisions to choose from: 1401, 1402, 1403, 1420, 1421, 1422, 1423, 1424, 1425, 1626, 1627, 1628

I manually tried all revisions down from 1628, untill i got the latest software without the DTC. = 1425.

So my conclusion is that rev. 1626, 1627, 1628 contains changes, that registers this error.
My conclusion is the same.
I have got the error after software update - unfortunately VW Dealer is not cooperative giving the feedback about the number.
The error showed up with delay 200km/2 weeks after the update.
There is official/internal VW procedure dated end of may 2022 to change the auxiliary hydraulic pump in case of error P0C2900 show up after software update -> the reason is production error ( mounting screw can be loosen damaging the whole gearbox)
There is official service kit for this job
I have decided to change the pump -> cost 1400 EUR in Poland.
The old pump looks OK, but the service told me there are few differences in mounting screws, o rings etc.
 

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Hey guys, Thought i'd share some of the information i've come across this far.

I'm a tuner based in Denmark, and recently purchased a 7.5R with DQ381.

I allways update to recent software made by VW, as they normally come with positive upgrades (there is some tombstones in between, which we know of.)
- And of course i did this aswell on ECU + TCU from revision 1402 to 1628, however i instantly achieved the famous P0C29 as you others.

For this car i had following revisions to choose from: 1401, 1402, 1403, 1420, 1421, 1422, 1423, 1424, 1425, 1626, 1627, 1628

I manually tried all revisions down from 1628, untill i got the latest software without the DTC. = 1425.

So my conclusion is that rev. 1626, 1627, 1628 contains changes, that registers this error.
For what it's worth, the original TCU version for my 2018 Alltrack DSG (DQ381) when it left the factory was 1406. After 23X4, it had been updated to 1644, so from the earliest to latest version:

Font Rectangle Screenshot Number Parallel

It's now been reflashed to back 1406 and is back to normal. VCDS will tell you the TCU part number installed in your vehicle, and you can then use that to look up the available software versions here by searching against your part number: www.dsgfiles.com
 

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Hey guys, Thought i'd share some of the information i've come across this far.

I'm a tuner based in Denmark, and recently purchased a 7.5R with DQ381.

I allways update to recent software made by VW, as they normally come with positive upgrades (there is some tombstones in between, which we know of.)
- And of course i did this aswell on ECU + TCU from revision 1402 to 1628, however i instantly achieved the famous P0C29 as you others.

For this car i had following revisions to choose from: 1401, 1402, 1403, 1420, 1421, 1422, 1423, 1424, 1425, 1626, 1627, 1628

I manually tried all revisions down from 1628, untill i got the latest software without the DTC. = 1425.

So my conclusion is that rev. 1626, 1627, 1628 contains changes, that registers this error.
Just to add - you mention that software updates normally come with positive upgrades, as would be expected.
Either that, or they may be designed to prevent a common fault or maintenance issue from arising. Or, in a well-known previous case, an update was designed to reduce emissions.
I've not been able to discover the purpose of campaign 23X4, which resulted in adverse changes in performance and, in some cases, appears to have caused a serious fault.
Is Volkswagen aware of this? VW Customer Service would only refer me back to the dealer, and not answer any questions. The dealer is not interested and tells me they have received no other complaints.
 

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Finally, today, I've had my car (2018 Golf Alltrack 2.0TDi 184 DSG) reflashed to original stock software versions for both ECU and TCU, reversing the 23X4 update. Relieved to say that it was immediately obvious how much better the car drives on the original software.
It has taken me 4 months and 2 false starts to find someone able and willing to do it.
Hi wear do you get it reflashed need mine doing
 

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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?
Hello mate I have same gold gtd mk7.5 2017 and just got this message today . What did u do to fix your situation
 

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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.
Matt - did you get anywhere with VW Customer Service? I didn't.

The value of a forum such as this is that it quickly becomes clear that multiple owners are experiencing the same issues and it can't be explained as coincidence. So it's frustrating that VW denies that they have caused a fault, will not respond to reasonable questions, cannot/will not put it right, and leave customers to find a 3rd party solution at their own expense.

By the way, anyone reading this discussion should note that even similar vehicles are running with different software versions both before and after the 23X4 update. Mine are not the same as yours.
 

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I have just had my car in for service and same here error code POC2900 gearbox error so turned around and took car straight back to vw 30 mins later tech comes to see me and explains problem with aux pump in DSG and has a full list of parts needed he also said that vw are aware of the issue and when updated may show this fault he did say that this was all covered by vw (I do have extended warranty) and was safe to drive and also any damage caused if any would be covered as this is still safe to drive.
So now awaiting for parts to be ordered and then a date when this can be completed I will update further once completed.
 

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I think I've been lucky in that 23X4 only caused my car to drive sluggishly (remapped gearbox and reduced power), but didn't throw up any gearbox errors pointing to an allegedly faulty aux pump. Maybe because my car has a DQ381 gearbox, which is think was only fitted in 4WD versions?? Interesting though, if VW is now "aware of the issue", which suggests they have had a significant number of complaints, whereas my dealer previously said there were none apart from me.
 

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The DQ381 comes in many front wheel drive versions.

My mistake - I'm not an expert in which Golf models have which DSG box. But after looking it up I found this:

"The newest transverse offering is the 7-speed DQ381, as introduced in the 2018 VW Golf R and 2019 VW GTI. It shares much of its design with the DQ500 and is rated for up to 317 lb-ft of torque with factory Mechatronic programming. Both the DQ500 and DQ381 transmissions offer even better fuel efficiency potential than the DQ250 with the addition of the seventh forward gear, along with their increased torque capacity."

I was guessing as to whether most of the Golfs mentioned here with gearbox error codes after 23X4 have a DQ200 or DQ250 box. But you're right, some 4Motion models had the DQ250 and lots of newer FWD models have the DQ381.

It seemed odd that almost everyone on here is reporting error codes pointing to aux pump failures, but mine didn't.
 
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