CFFB: Regeneration Won't End

Hi,

My VW Sharan II TDI (engine code: CFFB; mileage: 125,000 km) started a regeneration process today that simply won't end. Even after 2 hours of driving and 150 km, the idle speed is high, and the gear shift recommendation is still indicating regeneration.

I have never experienced this problem since I bought the car new, and I almost always perform the regeneration cycles (approximately every 450 km).

The values I can read out using VCDS (such as oil ash volume, calculated and measured soot mass) don't make much sense to me. Notably, the knocking sound that was often heard coming from the engine compartment after turning off the Sharan has been absent for quite some time. The error memory is empty.

Do you have any idea why I'm unable to finish today's recovery session?
Werden zur Fehlereingrenzung Infos via VCDS benötigt? If so, which ones?

Vorab vielen Dank für Eure Hilfe! Best regards.

PS: Please excuse me if this topic has already been discussed elsewhere. I couldn't find anything using the search function.

Check if the SCR catalyst is broken.

Sorry for what might seem like a stupid question.
Is there a way to tell if the SCR catalyst is broken? Are there any measurable values related to this? Or does it have to be removed for inspection?

Either tap it gently or remove the injector nozzle and use an endoscope to inspect it.

Goldparmaene wrote:

Sorry for what might seem like a stupid question: How can I tell if the SCR catalyst is broken?

Are there any measurable values related to this? Or do I have to remove it?
Hello,

It's difficult. If you have a single, combined catalytic converter and diesel particulate filter (CAT and DPF), rather than two separate units, you might experience excessive soot buildup in the exhaust pipe.

Knocking sounds when shaking or tapping the catalytic converter are also not a good sign.

Or by comparing the differential pressure with an identical model.

Assuming that regeneration doesn't end, I believe that either the pressure difference is already low at the beginning of the regeneration process, or the negative slope during the burn-off phase is too small for the software to detect the end.
Or, more likely, the DPF is clogged with deposits and a certain differential pressure is being exceeded, regardless of how long it is regenerated. This can be caused by, for example, incorrect engine oil (not low-ash), a high mileage with corresponding ash buildup, or excessive soot entering the system due to other engine faults.

Finally, the differential pressure sensor may also provide incorrect readings due to a defect or a faulty connection at the DPF.

Similarly, temperature management can be a contributing factor.

See:
}DPF not regenerating}

Thank you for your responses!

I can't say much. Just that what I consider to be the catalytic converter makes a purely metallic sound when tapped, and doesn't rattle or clatter, and that the inside of the exhaust pipe is clean and shows no signs of soot.

"I can read the differential pressure and determine if it's too low or too high. When the engine is off, it shows 6 hPa. When the engine is on, it shows 14 hPa. Should I observe the temporal development of this value during the regeneration process?"

Can I read the DPF fill level?

"Motor oil with longlife and low ash properties was always used."

Here are the values I still see:
Oil ash volume: 0.08 l.
Soot mass calculated: 1.52 g.
Soot mass measured: 18.38 g.

Comparison values for ash content:
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

0.08 liters is acceptable.

"Update: After the regeneration wouldn't stop, I drove the Sharan today with the regeneration running, as if it weren't (which I usually avoid), so I also stopped the car several times. And eventually, after stopping the car with the regeneration running and turning it off, and then driving again half an hour later, it seems the regeneration has finally stopped: When I read the data, I see plausible values that are not equal to zero for "Time since last regeneration" and "Kilometers since last regeneration" (yesterday, even after 200 km, the entries were always zero)."

Of course, I don't trust this "peace," but perhaps the problem can at least be contained now? Because the Sharan has indicated that a regeneration cycle has been completed, even though it wasn't finished automatically during the drive, but rather by me turning the ignition key.

I don't think there are any regeneration lines that have to run for over 200 kilometers.

Hello,

What are you doing? Why aren't you addressing my points?
No, there are no 200km regeneration cycles.

Sure, here is the translation of the text from German to English:

"LG" is an abbreviation for "Liebe Grüße," which means "Best regards" or "Best wishes" in English.

Hello,

I'm sorry that I haven't addressed your points yet. As a layman, I often find it difficult to evaluate certain procedures, which are trivial for an experienced mechanic. And when it comes to disassembly, I'm unfortunately often completely excluded from the process.

Do I understand correctly that the focus should be on the differential pressure? The differential pressure that I should compare with the differential pressure produced by another Sharan with a CFFB engine? I would first need to find that information.
Can we generally say what the differential pressure values should be? What are the values for a cold/warm engine, when stationary, before/during/after a regeneration?
Unfortunately, I am completely ignorant here, but I am happy to learn more .

Best regards.

Edit: I just found your post "Standard values for differential pressure," which I had overlooked before. I will start with that.

Yes, see:

Okay, I'm ready. Please provide the German text you want me to translate.

Hi everyone,

Here's my first attempt at a log entry, and I hope it's okay. I also have a few questions.

* How can I directly access the "data blocks"? Currently, I'm accessing the extended measurement values in the engine control unit "01-Engine Electronics," which I have to find individually, using the search function to help me.

* How do I correctly end the measurement? I can stop it, but then the option "continue" is always offered, which appends new data to the existing data. Should I end it using "back" or "cancel"?

* A new log file always has the same name as the old one. Consequently, should I change the name if I don't want to constantly append to the existing file, but instead want to start a new file?

"If I want to use KDataScope, it says that this function is only supported by the current generation of diagnostic interfaces. And after entering my email and password, I can purchase the KDataScope license. Do I already have this license, or do I need to purchase it?"

Now, let's move on to the log.

# CFFB
# Series
# 128,000 km
# Atmospheric pressure: 980 hPa, Intake air temperature: 8.0°C.
# Acceleration in 2nd gear, from 1000 to 4500 RPM.
# during regeneration (which, unfortunately, is being implemented again immediately).

Log file as attachment.

The recorded extended measurement data:
- Air mass: Actual value.
- Ambient air pressure
- Crankshaft speed
- Diesel particulate filter: Differential pressure.
- Diesel particulate filter: Oil ash volume.
- Diesel particulate filter: Calculated soot mass.
- Outdoor temperature
- Exhaust gas temperature sensor 1.
- Exhaust gas volumetric flow rate in the particulate filter.

Thank you for your help, Best regards.

Hello.

Goldparmaene wrote:

Hi everyone, Here's my first attempt at a log entry, and I hope it's okay. I also have a few questions. * How can I directly access the "data blocks"? Currently, I'm accessing the extended measurement values in the engine control unit "01-Engine Electronics," which I have to find individually, using the search function to help me.

Your engine control unit only provides extended diagnostic data. The combined measurement channels can be saved and loaded, so you don't have to reconfigure them every time.

Goldparmaene wrote:

* How do I correctly end the measurement? I can stop it, but then I'm always given the option to "continue," which appends new data to the existing data. Should I end it using "back" or "cancel"?

"back/cancel"

Goldparmaene wrote:

* A new log file always has the same name as the old one. Consequently, should I change the name if I don't want to constantly append to the existing file, but instead want to start a new file?

Okay.

Goldparmaene wrote:

"If I want to use KDataScope, it says that this function is only supported by the current generation of diagnostic interfaces. And after entering my email and password, I can purchase the KDataScope license. Do I already have this license, or do I need to purchase it?"

You're mixing things up now. Just read and understand what's on the screen. Please read it again carefully.

The note regarding the current diagnostic interface generation refers to VCDS and indicates additional capabilities with the latest hardware.

For KDataScope, it doesn't matter whether HEX-COM, HEX-USB, MicroCAN, HEX-USB+CAN, HEX-COM+CAN, HEX-V2, or HEX-NET was used for logging.

Every VCDS customer from Dieselschrauber already has a KDataScope (and KPower) license. This license is activated online within KDataScope using the login credentials (email/password) from the Dieselschrauber shop.

Goldparmaene wrote:

Now, let's move on to the log. # CFFB # Series # 128,000 km # Atmospheric pressure: 980 hPa, Intake air temperature: 8.0°C. # Acceleration in 2nd gear, from 1000 to 4500 RPM. # during regeneration (which, unfortunately, is being implemented again immediately). Log file as attachment. The recorded extended measurement data: - Air mass: Actual value. - Ambient air pressure - Crankshaft speed - Diesel particulate filter: Differential pressure. - Diesel particulate filter: Oil ash volume. - Diesel particulate filter: Calculated soot mass. - Outdoor temperature - Exhaust gas temperature sensor 1. - Exhaust gas volumetric flow rate in the particulate filter. Thank you for your help, Best regards

.
The differential pressure is much too high, which explains the regeneration problems.
Something might be clogging the DPF/exhaust system. Usually, it's ash buildup in the DPF, but the amount of ash and the mileage don't quite match up.
Are you the first owner of the vehicle? Just to be sure, the engine hasn't actually been driven 150,000 km more, and the DPF (Diesel Particulate Filter) hasn't been replaced, has it?

If the differential pressure sensor has been replaced, I would check to make sure the correct one is installed. Is the software in the engine control unit original?

If possible, inspect the exhaust system.

Best regards, Rainer.

Hi Rainer,

Thank you for your reply!

I am the original owner. The engine has only just under 130,000 kilometers on it, and the particulate filter has not been touched. The differential pressure sensor is original.
The software in the engine control unit... That's a good question, and it brings to mind: the VW diesel scandal. The engine was affected and received a modified software update at the time. It's likely that the software in the engine control unit was the one that was changed. However, that was quite a few years ago.

I would say that from the very beginning, I have been very careful about driving longer distances (almost never short trips) and ensuring that the regenerative braking is always fully utilized.

Here's a question: Is there a flap(?) on the Sharan that tends to get stuck and should ideally be cleaned annually? This is probably just my own limited knowledge, as I don't really understand it. I do know that the Sharan used to make a knocking sound more frequently after being parked. It sounded like someone was rhythmically tapping something in the engine compartment. I haven't heard that knocking sound for a long time. Is there an automatic mechanical "anti-clogging" function that might be defective?

Best regards.

"Edit: Would I notice a real blockage in the exhaust system based on the performance? I'm not seeing any changes. Or, if the performance feels the same, is it more likely that the differential pressure sensor is currently malfunctioning?"

And here are some further questions:

When I open KDataScope, the following dialog appears: "This version is outdated. Should we search for an update?" The version is 2.22, build 849. If I click "Updates," it says "No update available." Am I doing something wrong?

"If I want to create another log file on the same day without renaming the previously created one, which would otherwise result in appending, I can simply change the number of parameters to be included, as this number appears as a digit between the "&" and ".CSV"."

"As Rainer already mentioned, something seems to be blocking the exhaust system, as the differential pressure around the particulate filter is showing a value that is far too high. If I'm correct, it's about 4 times too high. Hopefully, only the corresponding sensor is providing incorrect data, and the rest is okay. I recorded some values during a drive of over 20 minutes (see the attached PNG file), which seems to suggest that the differential pressure sensor is working correctly? Ultimately, the differential pressure behaves similarly to the exhaust temperature and the exhaust volume flow, which is probably what we would expect? Or is the same sensor responsible for these three parameters?"

I have an appointment scheduled for next week at the repair shop I trust the least, as I myself am unlikely to be able to make any meaningful progress on the exhaust system. Hopefully, they will be able to provide more information there.

Thank you for your help, Best regards.

"Edit: What's strange is that so far, the Sharan doesn't indicate anywhere that something is wrong. Neither the engine warning light nor the particulate filter light is on. It's simply the constant regeneration process, which you only notice if you're familiar with the car."

Yes, great .

If you had uploaded the CSV file, I could now examine the corresponding operating points in detail...

Edit: It doesn't really seem like anything new, the differential pressure in the DPF is much too high. I'm confident that this is the reason for the endless regeneration.

The differential pressure sensor is relatively inexpensive and can be replaced very quickly.
Easier than inspecting exhaust systems or catalytic converters, for example. You might also have accidentally sat on something and crushed an exhaust pipe.

I can't help you with that; you'll need to check the exhaust system yourself. You might have connection points in the exhaust system to allow you to do a test drive with just the catalytic converter to measure the differential pressure. It's not that loud without the muffler.

I've also had exhaust pipes with broken internal components, which means the exhaust flow can be significantly restricted.