DPF regeneration every 600km, 2.0 TDI CFFB

Hello there,
I'm new here, my name is Lars, and I'm already having a problem with my brother's car:

The car has been in our possession for 6 months or 10,000 km, and since then, it has been regularly experiencing problems with the DPF (Diesel Particulate Filter). The dealer we bought the car from blames it on the driving style and isn't very helpful.


Here's a brief overview of the key details:
Golf 6 2.0 TDI, 103kW CFFB, manual transmission, has driven almost 153,000 km so far, and the "new" engine software has been installed for a few weeks.
Driving profile: Approximately 15 km of fast-paced driving on country roads twice a day, with occasional longer distances on the highway during weekends. I would consider the fuel consumption to be "normal"; a full tank allows for approximately 900 km of driving.

Now, let's get to the problem:
Every time after approximately 600 km, the DPF (Diesel Particulate Filter) light comes on and indicates that regeneration is needed. My brother always does that perfectly well, and then there's about 600 km of peace until the whole thing starts again.
Today, the car went into limp mode shortly after the DPF light came on. Luckily, it wasn't far from home. Upon arrival, I read the error codes using VCDS:

Error 8194, DPF P2458 00 (175): Regeneration duration.
Sure. Measurement readings:
Soot mass calculated: 24.13g.
Soot mass measured: 8.39g.
Oil ash volume: 0.09 l
The loading limit for field regeneration is 23.01g, therefore I suspect a fail-safe mechanism is activated.

Error memory cleared, limp mode deactivated, but the DPF light is still on.
I then tried to perform the service regeneration procedure while the vehicle was stationary, following the instructions provided in the technical articles. We stopped after 30 minutes, as we were holding the brake and accelerator pedals, but there were no changes in the measured values.

We then set off and tried to trigger something through the adaptation channel "DPF service regeneration during driving." However, when setting the "1" instead of the "0", an adaptation error occurred: "This control unit has not yet been coded..."

Since the DPF light was on, he initiated the regeneration process himself while driving on the highway.
After 30 kilometers on the highway, the DPF light turned off, and we drove home. Unfortunately, the VCDS laptop had run out of battery in the meantime. Back home, the readings were taken from the smart meter again:
Soot mass calculated: 5.53g.
Soot mass measured: -3.55g.

From now on, you can expect the DPF light to come on again within 600 km, requiring a regeneration process.


What's the problem here? Does anyone have any ideas?

Many other people in my family or circle of acquaintances with similar, or significantly shorter, driving patterns do not experience these problems.
The whole DPF (Diesel Particulate Filter) issue with this particular car (we have another 103kW TDI and a GTD in the family that are running perfectly fine, although they were purchased new) is now so frustrating that we've considered getting rid of it. Removing a DPF is, of course, illegal and not an option.

I have attached an auto-scan report after the regeneration process. If anyone needs further information, measurements, logs, etc., please let me know.

I would be very grateful for any answers or advice.


Best regards and have a lovely rest of your Sunday.

Lars.

Hello Lars,

It's not uncommon for regenerative braking to occur every 600 km, depending on the driving profile.
It's unusual that the regeneration process doesn't happen automatically while driving in your car; my wife's CFFB model works perfectly in that regard.

Since your car scan doesn't show any error codes related to preventing regeneration, I suspect there are faulty sensors that are providing incorrect readings to the engine control unit.

First, you should start with VCDS (mentioned). (Measurement values) to check the coolant temperature for plausibility, and then the temperature sensors on the DPF.

Also, also check if the coolant thermostat is working properly, otherwise the car will never warm up (the regeneration process only starts when the engine is warm).
The radiator inlet hose should not become warm when the engine is cold or lukewarm.

Best regards, Rainer.

Hello Rainer,
Thank you for the quick response.


Could it be that the regeneration process doesn't start immediately after the required water temperature is reached? It already takes quite a few minutes to cover 15km of country road in each direction, and the recovery process itself isn't something you can achieve in just 5km.


"You're mentioning that there might be sensor issues." I will check the cooling water temperature plausibility tomorrow, directly via the main control panel (MWB) and simultaneously with an infrared thermometer.
Do you know off the top of your head whether the thermostat for that engine is a standard bi-metallic thermostat or an electronically controlled one? It might also be possible to access it for testing purposes via the actuator diagnostics.

Temperature sensors on the DPF: Are there any target values for them?


Best regards,
Lars.

larrs wrote:

Do you know off the top of your head whether the thermostat for that engine is a normal bi-metallic thermostat or an electronically controlled one?

Sorry, my wife's car hasn't broken down yet.

If the engine control unit supports selective actuator tests, you can easily check with VCDS to see if any such tests are available.

The temperatures of the turbocharger and DPF are highly dependent on the load, and the temperature before the turbocharger is:
- Engine warm, idling, approximately 150-180°C.
- Full throttle, 3500 rpm, approximately 650-750°C.

The temperatures at the DPF are slightly lower. If the car has been stationary for a while (1 hour or more), the temperature sensors on the turbocharger and DPF should all display approximately the same reading.

Best regards, Rainer.

There are no set target values in that case.
With a cold engine, check all temperature sensors for plausibility.

larrs wrote:

Do you know off the top of your head whether the thermostat for that engine is a standard bi-metallic thermostat or an electronically controlled one? That could potentially be d

It contains a classic (and rather simple) bimetallic thermostat that is not diagnosable. The smart thermostats were only introduced by TDI starting with the MQB generation.


Please clear the particle filter learning values and register the DPF with "particle filter initialization" and your mileage of 150,000 km, so that the oil ash value returns to 0.09 liters. (You may need to test with more or fewer kilometers to achieve this.)

He starts a regeneration process as soon as he warms up.

We also had "problems" with our EA189 (a DPF malfunction message), but it didn't trigger a warning light, just an entry in the system.

I couldn't find anything unusual, and then I proceeded with the action from the top. Since then, I haven't had a single error entry.

Also, please check if your coolant temperature is above 60°C. And most importantly, please check if your system passes the automated test sequence, or if your AGR (Arbeitsgemeinschaft für Rehabilitation - Rehabilitation Working Group) "passes" the relevant requirements.
Because the regeneration process is blocked if the EGR valve actuators are not functioning correctly.

Sure, here's the translation:

"Hello."

Hello,
Thank you again for the answers. I'm sorry, I only just got around to replying; work commitments came up.


Yesterday morning, I read out the following data from the engine while it was cold:

Coolant temperature: 4°C.
Coolant temperature at the radiator outlet: Is: 3.4°C.
Engine oil temperature: 3.5°C
Exhaust temperature sensor 1: 20.0°C (this definitely cannot be correct)
Exhaust temperature sensor 2: -0.0°C
Exhaust temperature sensor 3: -20.5°C (which also doesn't match the outside temperature)
Exhaust temperature sensor 4: -4.5°C

Unfortunately, I haven't found any specific information about the temperatures at the DPF. Could the temperatures mentioned above be relevant? How to interpret exhaust gas temperatures?


I'll do that again while I'm driving. However, because my brother is on vacation, the car is still in the garage until tomorrow. I'll also check the coolant temperature "live" to see when and if the thermostat opens.

@Blackfrosch:
Thanks for the tip about the learning values and AGR. I'll check what I can find about that in VCDS and try it out.


Best regards,
Lars.

Exhaust temperature sensors 1 and 3 each have their minimum values at the posted values. Please check it while the engine is idling, and also while driving.
Idle speed is best - because after a while, almost everyone should be showing roughly the same reading.

Sure, here's the translation:

"Hello."

Okay, it's me again.


We have already done the things that @Blackfrosch described.

Automatic test sequence of the AGR system: Completed, System test end: System is functioning correctly

DPF learned values have been erased and re-initialized. The regeneration process was initiated by MSG and subsequently carried out.


Regarding the temperatures:
Five minutes after my brother arrived home, I plugged in VCDS, started the engine again, and read the following temperature values:

Coolant temperature: 69°C
Coolant temperature at the radiator outlet: Is: 44.1°C.
Coolant temperature at the radiator outlet: Target: 80.0°C.
Exhaust temperature sensor 1: 142.1°C
Exhaust temperature sensor 2: -0.0°C (apparently, the sensor is not present in our system)
Exhaust temperature sensor 3: 100.9°C
Exhaust temperature sensor 4: 115.8°C

The coolant temperature at the outlet of the radiator, as indicated, seems to me to be an initial sign that the thermostat is working correctly. Otherwise, the temperature would be similar to the measured coolant temperature.

As we "had" to take another regeneration trip as mentioned above, I also logged the data again and, at the beginning, I kept the engine speed quite high.
At the beginning of the journey:
Coolant temperature: 89°C
Coolant temperature at the radiator outlet: Is: 88.8°C.
Coolant temperature at the radiator outlet: Target: 80.0°C.
Exhaust temperature sensor 1: 408.9°C
Exhaust temperature sensor 3: 391.4°C
Exhaust temperature sensor 4: 423.7°C
Particulate filter: Differential pressure: 9 hPa.
Particulate filter: Oil ash volume: 0.09 liters.
Particulate filter: Calculated soot mass: 24.01g.
Particulate filter: Soot mass measured: 7.86g.


Towards the end, just before my laptop battery ran out again, I drove another 10 km on the highway at 2000 rpm, and the soot mass continued to decrease.
Coolant temperature: 89°C
Coolant temperature at the radiator outlet: Is: 88.1°C.
Coolant temperature at the radiator outlet: Target: 80.0°C.
Exhaust temperature sensor 1: 698.5°C
Exhaust temperature sensor 3: 489.7°C
Exhaust temperature sensor 4: 587.3°C
Particulate filter: Differential pressure: 63 hPa.
Particulate filter: Oil ash volume: 0.09 liters.
Particulate filter: Calculated soot mass: 17.47g.
Particulate filter: Soot mass measured: -1.62g.



Unfortunately, I didn't log the motor speed, which would be interesting in relation to the differential pressure, wouldn't it?

Does anyone have any other ideas about what it could be?
We bought an OBD Link LX for my brother today. Once it arrives, he'll be able to monitor the diesel particulate filter (DPF) on his phone using the VAG app. I also don't have the time every day to work on my laptop while I'm at the car.
Since the car is always driven at very low RPMs, I'm concerned that the system might not be working properly, and that it never really gets warm, especially in the winter. However, the problem also exists in the summer, even at 30°C.

Next week, I'm going to try driving the car every day to see if we can make it work. That way, it will accumulate 400 km of highway driving in a week, and I'll check the readings again then.


Best regards,
Lars.

Next time, please record the duration of the post-injection periods. However, according to your logs, it appears that the system is always regenerating.

And: If a "source of smoke" is constantly producing smoke or particles, for example, due to a faulty turbocharger or an incorrect engine oil level. Leaks in the charge air system, etc., will prevent the DPF from completing its regeneration process.

My suggestion would be to log the state of charge for at least approximately 50 km after (!) a successful or forced regeneration, while specifying the operating conditions (e.g., city traffic, highway - slow/fast, etc.).
Instead of continuous logging, for example, read the load state every 10 km and click "Save" in VCDS. Then you can see how the value develops and adjust the intervals accordingly, making them larger or smaller.

I have a CFFB here for comparison, to see how quickly the diesel particulate filter's loading level increases.

Best regards, Rainer.

Furthermore, it is not clear to me at this time whether he has successfully completed the recovery process. If you run out of "juice" there, that's one thing, but it also has an increased idle speed while it's regenerating.

"Your problem is that the indicator light comes on after 600 km (and doesn't self-regenerate), and then you have to take a regeneration trip for it to clear, which, according to Lars' statement, does work (the light goes off again after another 600 km)."
What Rainer says doesn't quite make sense to me, because if he has a "source of soot," he would start regenerating it early on.

Quote:

Next time, please log the duration of the post-injection events, but according to your logs, it always seems to regenerate...

Why? You can see from the temperature in the DPF that there is enough heat for regeneration. If regeneration is not running, there won't be 500°C in the DPF - and there won't be a post-injection. Of course, this also serves as an indicator of whether regeneration is occurring or not -> but regeneration is running, and it's burning particles. Even if he didn't stop her, the light wouldn't come back on after 600 km; instead, she would likely experience oil dilution.

As far as I can tell from the values, everything looks plausible and good to me, and I'm 95% sure that the error related to resetting the learning parameters won't reappear. Please check the loading status/mileage regularly.



Sure, here's the translation:

"Hello."

Thank you at least for your responses.

Of course, I will continue to keep you updated. That's why we also purchased the OBD adapter and the app.

According to my experience, the 10km of highway plus the distance from the highway to our village should have been sufficient to complete the regeneration process after the computer failed. We performed the regeneration while driving, not while stationary. I can gladly double-check that again tomorrow.
Is there a soot mass value that, when measured or calculated, indicates that regeneration is complete? The engine control unit does not initiate forced regeneration when the vehicle is stationary. Previously, I performed the VCDS test, which involved keeping the accelerator pedal fully depressed and the brake pedal pressed for 20 minutes in the driveway, but the soot mass value remained unchanged.


Let's see what happens... you'll definitely hear from me!

larrs wrote:

Is there a soot mass value that, when measured or calculated, indicates that regeneration is complete?

Approximately 5-7 grams of calculated soot mass.

Okay, it's me again .


I just checked the car's computer again:
Particulate filter: Calculated soot mass: 13.34g.
Particulate filter: Soot mass measured: 4.24g.
Particulate filter: Kilometers since last regeneration: 136 km.
Particulate filter: Time since last regeneration: 202 minutes.

We drove about 20 km on the highway, and the amount of soot continues to increase...

At what loading levels/temperatures does the DPF initiate automatic regeneration?

Best regards and have a great start to the weekend!
Lars.

I think around 25-30 grams.