[Quadrant55]

Who is Srinivas?
Read my post about his FNG (German Motors - FNG in Hyderabad).

Background

Had recently visited German Motors to pick up my car and Srinivas was working on a DQ 200 mechatronics unit which was dismantled to the bone on his work bench.
So, I thought about picking his brain about its issues and what followed was a long Q&A session.
I later felt I should have probably recorded the complete conversation, it would have made writing this a whole lot easier. For now though, I have reproduced our conversation below to the best of my memory.

What follows below is not the exact order of the conversation. I have edited and rearranged some of it for tone and flow purposes.
Everything in bold is either my query to him or explanation to the reader. The rest is Srinivas’s voice

Issues

Why are there so many issues with the DQ200?
There are probably three main causes - Mechatronics, Clutch, TCU/M. Most times repeated failures are due to different parts failing one after another.
The major culprit is the mechatronics unit. To put this into numbers, off the 20 DQ200 cases we handled in the past few months (they are averaging 4-6 DQ200 cases per month and are unable serve at least another 2-3 due to lack of time and manpower) 14-16 were mechatronic failure. Of these barring 3-4 (which had an additional issue of clutch or TCU along with mechatronics), the rest had mechatronics as the only issue. That’s almost 80% of the failures.


Mechatronic unit with the back cover off


Other side of the Mechotronic unit with the TCU removed. You can clearly see the plugs which connect to the TCU. And with the accumulator removed

What’s the reason for the Mechatronic (mech) failures?
The fragile design of the mech unit sets it up for easy failure. Even in the mech unit, it is mainly the accumulator housing plate (its even called the valve body plate or accumulator body) that is causing the issue. The housing plate is made from aluminium and the walls of this housing (where the accumulator screws in) are quite slim and are unable to with stand the 60-70 bar pressure the accumulator generates. Over a period of time micro cracks occur and the accumulator fails to build enough pressure. This initially results in jerky or hard shifts. From there it just goes downhill.


Completely dismantled housing plate. Rear of the plate. Look at the intricate pattern for oil flow. This brittle wall is unable to withstand pressure


The dreaded - P17BF & P189C DTCs point to a clear case of crack in housing .The issue starts with micro cracks like this. But this whole area is now compromised, as time passes the crack only spreads

Does that mean the mechatronics has failed and the car won’t move?
Well, yes and no.

• Yes, the mechatronics has failed in the sense that once there is a crack, the housing plate it can’t be repaired. The crack/s can’t be plugged or welded etc. And even the accumulator gets damaged (it loses pressure) if there is crack in the plate. So even a small crack would mean both the housing and accumulator have to be replaced.
• No, the car will still drive and very few people will notice the jerks and hesitant shifting initially as it happens very sporadically. But as time passes the crack(s) only grows in size and the accumulator struggles to build enough pressure. In a bid to create the necessary pressure it starts to overwork, at which point the TCU activates pump protection protocol (anti-play protection), which is a measure to make sure the accumulator is not overworked and doesn’t overheat. This results in car being stuck and unable to change gear. This is a clear indication that the mechatronics is done. But even after this the car will drive. You just need to turn off the ignition and restart the car, it will drive normally for some distance (sometimes even few days or weeks can pass) before the issue reoccurs. Unfortunately, most owners don’t understand that this is just a limp/safety mode and continue to drive in this manner for months which exacerbates the issue.

How can it get worse if the accumulator and housing need to be changed anyway?
In the initial stages it is just the accumulator and housing which will need replacing but as the issue aggravates the hydraulic pump and motor will fail due to overheating. And even before they fail sometimes some of the solenoids might give up etc. Overtime a bad mechatronic will affect clutch life too as inconsistent hydraulic pressure doesn’t allow the smooth and accurate engagement of the clutch. In extreme cases even the gear cogs get affected.


When you don't address it on time - aluminium will break off like a biscuit . This car's clutch also took the burnt of the neglect and had to be replaced

What about the other issues – Clutch?
I actually don’t see clutch replacements as an issue/defect. Clutches are normally wear items. And its very common for us to change the clutch even in manual cars. Most get their clutch plates replaced/overhauled between 60-100k mark. So, why is no one complaining of clutch issue with manuals?

In my view, (after the clutch lining improvement) the clutch life is mostly down to driving style and usage mix. I have recently replaced the clutch for a car(with DQ200) which did a little over 1,30,000 kms on its factory clutch. On the other hand, I have even seen some which failed at 35k kms. So, in my view this is a general wear issue, purely down to driving style and usage.

If that’s the case, why is clutch replacement considered a major issue with these gearboxes?
Due to the cost involved (compared to manuals DSGs clutches are quite expensive) and because its not the norm with other auto-boxes. DSGs have got a bad rep because they are probably unfairly compared to the other auto-boxes which usually don’t face this issue. But we need to make a clear distinction, DSG is unlike the other auto-boxes. It’s essentially a manual gearbox with 2 clutches controlled electronically. Or some might even say its two separate manual gearboxes and clutches with automated operation. The accumulator essentially takes over the function of your left foot.

So, when compared to torque converters & CVTs regular clutch replacement stands out as a red flag. With periodic maintenance other auto-boxes will do 3-400,000kms or more without any major parts needing replacement. But a majority of DSGs will struggle to touch 100k kms without a clutch replacement. Have you heard of same for the ZF 8 speed? Most probably not (after this he went into vivid detail about the design differences between Torque converters and DSG. About planetary gears, how the torque converter clutch discs are different, what ZF does differently to other torque converters et al. I have chosen not to reproduce that part here as I don’t recall the whole bit accurately and don’t want to misquote him. Will probably tackle this in a separate post later. Next time, will go prepared with a massive cup of coffee and notepad )

And TCU?
There are two main causes for TCU issues – heat and corrosion. Excessive heat is the enemy for any circuit board. The TCU is no different. Overtime this results in malfunctions or complete failure. Unpredictable gearbox behaviour (failure to engage certain gears, delayed or premature shifting) is a clear sign of a bad TCU.

The TCU connectors are another weak link, they corrode or fail due to overheating quite easily and this throws up multiple DTCs(Diagnostic Trouble Code). Most of the ‘short to ground’, ‘selector cannot be regulated’, ‘multiple gears engaged’ DTCs from the P170 series (172/3/4/6/7) are related to TCU miscommunication. A major cause of this is bad connectors.


TCU connectors corrode or fail due to overheating. The connector is part of the TCU frame. Multiple connectors which connect to the car and to the valve body/mech unit

Any other issues?
There are others like the gear selector issues – basically the gear selector fails and we won’t be able to engage that particular gear – like reverse or second gear. Sometimes bearings fail or the DMF (dual-mass flywheel) fails. But most of these are addendum issues. They happen because of abuse/misuse of another malfunctioning part. They generally don’t get triggered on their own.

Do these gearboxes under-perform once repaired? (I asked this because many members here had reported performance issues after repairs)
This is not that common. But will happen if the issue was misdiagnosed or repair job was botched. The measurements are very precise and tolerances are unforgiving. So, mistakes can happen. At times adaption might have been performed poorly.

What do you mean by misdiagnosed?
Diagnosing these issues is not as straight forward as we would like it to be. Most of the times during initial diagnosis/scanning, multiple DTCs show up. So, codes related to all three – mechatronics, clutch and TCU (or two of those parts) might show up. But usually, the actual cause might only be one of these parts. Like 60-70% of the time, the rest might be issues with two parts. Issues with more than two of these is generally rare. It only happens if the car is used for a very long time without addressing the preliminary issue. So, its quite easy to think that there is an issue with the mech unit instead of say the TCU or vice versa.

So, initial DTCs might have false positives?
Yes, most definitely. This is mainly true for multi-brand scanners like Launch or Autel. OEM diagnostic software (ODIS in this case) are better but even they throw up random codes at times. There are even times when no DTCs come up but the vehicle gets stuck in gear. This might happen in the beginning stages when the housing plate has just developed crack leading to temporary pressure loss. It might not even register as a DTC.


This crack never registered as a DTC. But the car was stuck in gear a couple of times.

Sometimes the DTCs might point to a problem. But the cause might not be evident right away. Once after scanning there was a pressure loss DTC(as shown in pic below). But we were unable to identify any cracks. In the end we were able to pin it down to a defective valve body which was contaminating the oil which in turn choked the filter. At the ASC the only solution for this is a complete mech unit change. Will probably cost 200k. Luckily, we were able to find a used valve body (not easy as in the used market they sell it along with the TCU which increases cost). And the customer saved probably 70-75% of his money.


Even a choked filter might lead to a pressure loss. The car might be stuck in gear or might just stall.


The filter and separator plates(these child parts are not easily available in India and are expensive) were also changed and issue was resolved.

How do you identify the actionable DTC?
That is ultimately down to the technician. A good long test drive will give us a better idea of the issue. We try to see if the issue can be replicated by us. With experience we would able to get it right around 95% of the time. But there will be times when we get curveballs where even our experience doesn’t help.


P177 series errors are notorious and the severity can range from minor to critical failure. Gauging the severity is crucial.

For instance, we had a car which had P177C – short to ground error. In our long test drive, we noticed some clunking noise. This a clear sign that the multi-clutch has gone bad, but the error never showed up even after multiple scans.

• And a ‘short to ground’ error in transmission electronics is related to the TCU. Nine out of ten times the solution for this error is to replace the TCU. But at times running the adaption settings might clear this error. So, every time we get this error we run the adaption first, test it for a couple of days and then if necessary change the TCU.

So, to get rid of the P177C we tried the adaption. When that didn’t work, we changed the TCU and the error was gone. Went for a couple of long test drives to see if the clunking noise would reoccur. It didn’t. So, we informed the customer that the clutch might be issue and delivered the vehicle. A month later the car came in again(was stuck in gear, no banging) and this time when we scanned it clearly showed clutch mechanical failure. So, we were not sure why it didn’t show that DTC before.

[Quadrant55]

Solutions

What options do we have to fix these?
Depending on the extent of damage there are multiple options.

Mechatronics
Volkswagen Group knows the exact cause of the issue and sells a repair kit in EU (The kit includes the housing plate, an accumulator, filter and few seals) and other markets because of their ‘right to repair laws’. In India, that’s not the case. The kit is available but only at ASC. If FNGs like us need to buy it we need to pay the full price of 75-80K to get it. (Based on some posts here ASC seems to be charging 100-130K for mechatronic repair inclusive of labour and taxes)

In Europe the same kit is available for much cheaper. Can be imported for probably less than 60K.
And then there are Chinese kits which are an exact replica of the VW repair kit(but cost much less) and you won’t be able to tell the difference. Many independent workshops use these kits but the failure rate is very very high.


The kit includes the housing plate, an accumulator, filter, separator plates (known also as valve gasket) and a couple of seals/gaskets. (Pic from web)

There are many speciality manufacturing firms in Europe which produce a very ingenious repair kit. These kits come with a steel cap, accumulator, some seals and specialized silicon grease. If needed the filter and separator plates can also be ordered additionally. There are many advantages with these kits. They are better and cheaper than VW’s kit. And much easier to install. You don’t need to remove the extra bits like solenoids, hydraulic motor, pump etc to replace the housing plate. And the best part is the steel cap can withhold much higher pressure than VW’s housing.


These are a much better option than the VW kit. These kits are even easier to fix and cheaper


Don't need to remove the old housing. This cap just sits in the existing housing and needs to screwed in.


New accumulator with cap installed in existing housing

The only issue with these kits is that we need to be very precise. Every manufacturer has a different torque rating. Go above or below the prescribed rating while tightening and these will also fail. So, we need to extra cautious.


An improperly fixed one can shred the O-ring to pieces. Why this happens? See below


Srinivas drew this on a paper to explain to me the water-jet effect. I just recreated the one on the right for easier understanding

Clutch
The only solution is to get it replaced. You have a couple of options. One is the Sachs kit and another is the LUK kit. There is hardly any difference. But there is a common misconception that Sachs is OEM and LUK is aftermarket, that is not true. Both are OEM suppliers and are good quality. They are some specialised tools needed for removal, installation and measurement. They are expensive and can’t be used for anything else. Companies like LUK and Laser Tools sell these kits.


The installation & removal kit is separate from the measurement kit

Similar kit from LUK. One on the left is for removal & installation. One on the right is for measurement(Pic from web)

Although he didn’t mention the price to me. I googled them and these are expensive.
The complete Laser kit is priced above 100K and the Luk one seems to be even more expensive.
(After showing me the kits. He gave a detailed explanation of why the accurate measurement during installation is a must. About release bearing stiffness, minimum tolerance, shims thickness etc. This frankly went over my head . So unable to reproduce it here)

TCU
For any TCU issue the only solution is replacement. Even if its only a connector issue it needs to be replaced. Unfortunately, they are not repairable. There are no child parts. The connectors are part of the TCU frame (see pic in the previous post). The complete plastic frame with the TCU needs to replaced.
A new one here cost almost 80K. Used one will be cheaper but its hard to get only the TCU in the used market. It is generally sold with the mechatronic valve body which increases the cost of the used part. So, if you have issues with both the mech unit and TCU, a used one can be considered. But I wouldn’t suggest it, as there is no way to know it’s actual age or usage history. There is a very high chance of it failing again.

In my view, the best solution is a re-manufactured/refurbished TCU. These can be imported from Europe. After duties and taxes these would have a landed cost of around 45-50K. At most independent workshops you will probably spend another 10-20K as removal, installation and coding charges. So, a max of 70K probably. (I checked here for a cost comparison with ASC but couldn't find any details)

Just a note of caution - There are Chinese replicas of this too for probably as low as 35K but there have been multiple complaints about these breaking down in less than a year and some for being un-code-able.


Re-manufactured TCU imported from Europe

Winding Up

Has the DQ 200 been improved/updated?
Yes, it was improved almost a decade ago. But the issues tackled during that improvement were different. Initially the issues were related to shorting of TCU (which resulted in the complete failure of the mech unit), hard or inconsistent shifts and premature failure of the clutch pack.
The changes made to fix these issues were;

• Synthetic oil was replaced by mineral oil. As synthetic oil had corrosive additives which were eating away the main mechatronic seal. And was conducting electricity and shorting the TCU/Mech unit. All oils conduct electricity but synthetics are much more conducive compared to other oils. So, this solved the shorting issue.
• The accumulator seal was improved as the older seal was unable to hold necessary pressure.
• And the clutch lining was improved. They changed the material composition

The brittle accumulator housing plate which is the cause of almost 90-95% of the present Mech issues has not being improved at all.


Clutch lining was improved almost a decade back

Does that mean the newer batch of Volkswagen Group models – Taigun, Slavia etc will also face this problem?
In my view, most definitely yes. Its only a matter of time. Although I must mention that a couple of VW technicians claimed that the housing wall thickness has been increased. But I can neither confirm nor deny this as I haven’t personally opened any mech units on the newer models.

So, they might be better?
Well, can’t comment much on that as I am unsure of the improvements made. But if the only thing they did was improve the wall thickness without changing the material then there isn’t much hope as it is only delaying the inevitable. As I said only time will tell.

Final Note
This is to the best of my memory. In some places I might have paraphrased what Srinivas said for continuity or easy understanding. Hope I haven’t misquoted him anywhere. Most of the pics were either clicked by me and some were shared by Srinivas (fault code and old case pics). A couple were taken off web (mentioned below pic).


Mechatronic Oil. And a few other Volkswagen Group oils.


Pop Quiz - Anyone want to venture a guess on what this is?

[Aditya]

Thread moved out from the Assembly Line. Thanks for sharing!

[FAIAAA]

Thanks for sharing. Truly a technical masterclass.

One question - would this also be the case with the Hyundai /Kia 7 speed DCT gearboxes mated to turbo petrols? Or are they built differently /better? All their turbo petrols (Verna, Creta, Alcazar, Venue, Sonet, Seltos, Carens) come with this gearbox.

Given their sheer numbers, are they a ticking time bomb once they cross 40-60K kms or should we be at peace?

[100Kmphormore]

Very detailed information - bookmarked!

The main reason I dislike Skoda/VW cars and several of my friends who moved to the manual Rapid/Jetta/Polo diesels in 2017-19, will never own one is simply of this dratted DQ200 gearbox and the herald of when they might give up, especially after 50-60K km in our conditions. The service center experience matches it as well. Many have moved on to BMWs and why not! Man the ZF8 has far more reliability though being more complex and used in 50L+ cars. The Polo GTI, Octavia 1.8 TSI, the Kodiaq/Tiguan petrols - these have to be a tad more reliable to own. Of what use is that opulence and premiumness otherwise if it requires a pampering like a premium car sitting in the premium economy segment?

[SS80]

Thank you so much for sharing such valuable and insightful information about this often-discussed gearbox. I’ve always wondered what could have caused such chronic failures in a product of this caliber. Now, the lingering question is: how did the German engineers not identify or opt to change the material of the accumulator cap? Was there a specific reason for sticking with aluminum instead of switching to steel or a steel alloy? Could heat-related properties have been a deciding factor?

Regardless, I’ve bookmarked this thread because it’s an incredible resource. I truly appreciate the effort you put into creating this detailed and enlightening write-up. Thank you once again!

[Col Mehta]

Brilliant! Thank you for such a detailed write-up.

And what a timing of this thread. The 2020 Creta 1.4 DCT in our extended family with ~75k kms just went in for the dreaded DCT repair - I'll get full details by tomorrow, all I know is the shifts had gotten even more jerky.

Not surprised that these DSGs/ DCTs are unreliable over long runs. They are ill-suited for our hot and dusty environment and manufacturers should seriously consider offering more reliable options to consumers.

[shardul_pathak]

This Article is god sent for me, I have a 2015 Polo GT, 1.2, and the fear of a gear box trouble is always looming at the back of my head.

Although I had it looked into at @Viraat's garage in Delhi last year and small niggles like, delayed slotting into "R" and first gear were rectified by a simple mechatronic oil renewal, I was always looking out for subtle hints of developing issues.

I love that car to the brim and it has clocked a little over 100K on the ODO, is there a preventive maintenance that we can do to avoid issue to the DQ200 as well?

Its a huge relief to know of these repair kits, but the cost involved and availability at ASC will always be an issue. Are there any FNGs in Jaipur, which fellow BHPians have used and are would recommend?

[Jeroen]

Outstanding! Thanks for sharing. Good to see such a detailed story!

Jeroen

[ads295]

This is A grade reading material right here! I always wondered why exactly this trans was plagued with issues, and you explained everything perfectly. I was glued to the entire post. Thank you!

[vanguard]

Originally Posted by Quadrant55

Solutions

Amazingly detailed information. Truly a gem.
Did you get a chance to confirm with Srinivas.. Do we need to change the oil in mechatronic after a certain interval or we go blindly with sealed for life story as told by the OEM.

[GeeTee TSI]

Brilliant insight and context, coming as some consolation to affected parties! This technical root cause is exactly what one never gets at the ASC, while FNGs with this sort of know-how are few.

A rather sobering takeaway being the discriminatory practices where 'Right to Repair' laws are non existent. We face the double whammy in India along accelerated damage due to the harsh usage conditions.

Strangely comforting to know the mystery behind the failures, any preventive measures to delay or avoid such crippling damages to the DSG?

[phamilyman]

Originally Posted by Quadrant55

And the best part is the steel cap can withhold much higher pressure than VW’s housing.

What an amazing thread - this is the reason why Team-BHP is singularly unique globally, thanks to amazing posters like you!

What you mentioned here, reminds me of the SpaceX vs NASA design philosophies

Columbia disintegrated upon re-entry because of damage to the thermal protection tiles above the fuselage made from aluminum.

SpaceX needs a much simpler thermal tile design because their rocket is made from steel (SS304) which can withstand higher temperatures / pressures!!

We see the same problem statement / solution here :-)

[Auto_guy_101]

What a read! This is pure gold material. Thanks for sharing.

Onto a slightly more concerning topic: yes, the India 2.0 DQ200 is probably nothing short of a ticking time bomb. It's been about 3-4 years for them in the market and I think issues might start showing a little over the 6-7 year mark. I have 2 interestinh questions for Mr. Srinivas:

1. Assuming Volkswagen Group survives in India to launch their 8 speed TC unit (say they do it for the 1.5 TSI as well), is there any possibility of a gearbox overhaul for broken DQ200s? I'm sure anything under 2L would be reasonable to most DQ200 owners. I know this question perhaps sounds baseless, but I'm asking because ASC will definitely not attempt this, much less agree to it or even think of it.

2. Is there a competent diagnostic that could be performed periodically to spot DSG issues early on? Again, Volkswagen Group probably won't bother to do this, but if there's something fool proof, maybe all of use with a 5 yr+ DQ200 could incest in it.

[rageshgr]

As an owner of a 9 year old Polo GT 1.2 TSI, this was a very intersting read. Some of the information is pure gold. Thanks for sharing.