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 influenced by the need for regeneration.

I have never experienced this problem since I bought the car new, and I almost always fully discharge the battery (through regenerative braking) approximately every 450 kilometers.

The values I can read out with 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 regeneration process?
Is information needed via VCDS to narrow down the source of the error? If so, which ones?

Thank you in advance for your help! LG

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

Check if the SCR catalytic converter is broken.

Sorry for what might seem like a stupid question:
How can I tell if the SCR (Selective Catalytic Reduction) catalyst is broken? Are there any measurable values that indicate this? Or does it need to be expanded?

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 (Selective Catalytic Reduction) catalyst is broken? Are there any measurable values that indicate this? Or does one have to remove it?

Hello,

Difficult. If you have a single integrated KAT (where the KAT and DPF are combined) instead of 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 that of an identical model.

Assuming that regeneration doesn't end, I believe that either the differential pressure 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 be giving 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 don't have much to say. Just to clarify, what I consider to be the catalyst sounds purely metallic when tapped, and doesn't rattle or clatter, and the inside of the exhaust pipe is verschandeln and shows no signs of carbon buildup.

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

Can I read the DPF fill level?

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

0.08 liters is acceptable.

News: 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, the regeneration seems to have 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 damage 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 removing 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's the translation:

"LG" translates to "Best regards" or "Sincerely" in English.

Hello,

I'm sorry that I haven't addressed your points yet. As a non-expert, I often find it difficult to evaluate certain procedures, which are trivial for an experienced mechanic. Unfortunately, when it comes to taking things apart, I'm often completely left out of the process.

Are you saying that the focus should be on the differential pressure? The differential pressure that I should compare to the differential pressure produced by another Sharan with a CFFB engine? I would have to find it first.
Can we roughly estimate the values that the differential pressure should have? With a cold/warm engine, at a standstill, before/during/after regeneration?
I am unfortunately completely ignorant here, but I am happy to learn more .

LG

Edit: I just found your post "Differential pressure normal values" that I had overlooked before. Here is where I will start.

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 (ECU), specifically in the "01-Engine Electronics" section. I'm selecting these values individually and using the search function to help me find them.

* 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. Do I close with "back/cancel"?

* A new log file always has the same name as the old one. Consequently, would I need to change the name if I want to start a new file instead of constantly appending to the existing one?

"If I want to use KDataScope, it states 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 these, or do I still need to buy them?

Okay, let's move on to the log:

# CFFB
# Series
# 128,000 km
# Atmospheric pressure: 980 hPa, Intake air temperature: 8.0°C.
# Acceleration in the 2nd [grade/year/etc.] Speed range 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: Raw value.
- Ambient air pressure.
- Crankshaft speed.
- Diesel particulate filter: Differential pressure.
- Diesel particulate filter: Oil ash volume.
- Diesel particulate filter: Soot mass calculated.
- 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 (ECU), specifically in the "01-Engine Electronics" section. I'm selecting these values individually and using the search function to help me find them.

Your engine control unit only has extended diagnostic data. The configured measurement channels can be saved and loaded, so that they don't have to be reconfigured 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. Do I close with "back/cancel"?

"back/cancel"

Goldparmaene wrote:

* A new log file always has the same name as the old one. Consequently, would I need to change the name if I want to start a new file instead of constantly appending to the existing one?

Okay.

Goldparmaene wrote:

"If I want to use KDataScope, it states 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 these, or do I still need to buy them?

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

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 of Dieselschrauber already has a KDataScope (and KPower) license. This will be activated online within KDataScope using the login credentials (email/password) from the Dieselschrauber Shop.

Goldparmaene wrote:

Okay, let's move on to the log: # CFFB # Series # 128,000 km # Atmospheric pressure: 980 hPa, Intake air temperature: 8.0°C. # Acceleration in the 2nd [grade/year/etc.] Speed range 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: Raw value. - Ambient air pressure. - Crankshaft speed. - Diesel particulate filter: Differential pressure. - Diesel particulate filter: Oil ash volume. - Diesel particulate filter: Soot mass calculated. - Outdoor temperature - Exhaust gas temperature sensor 1 - Exhaust gas volumetric flow rate in the particulate filter. Thank you for your help, Best regards

.
The pressure difference is much too high, which explains the regeneration problems.
Something might be stuck in the DPF/exhaust system and causing a blockage. Generally, the ash in the DPF is the problem, but in this case, the amount of ash and the mileage don't seem to match up.
Are you the first owner of the vehicle? It's not that the engine actually has 150,000 km more on it, or that it has an old DPF that needs to be replaced.

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... Good question. Keyword: 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. That was quite a few years ago, though.

I would say that from the very beginning, I've paid close attention to driving longer distances (almost never short trips) and ensuring that the regenerative braking is always used fully.

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. However, I do remember 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-vibration" function that might be malfunctioning?

LG

Edit: Would I notice a real blockage in the exhaust system affecting performance? Which I'm not seeing. Or, assuming the performance seems to be roughly 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 existing one, which would otherwise result in appending, I can simply change the number of parameters to be included, as this number appears as a value 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 are these 3 parameters measured by the same sensor?

I have an appointment scheduled for next week at the workshop I trust the least, as I myself am unlikely to be able to effectively work on the exhaust system. Hopefully, we will be able to say more there.

Thank you for your help, Best regards.

Edit: What's strange is that so far, the Sharan isn't showing any signs of a problem anywhere. Neither the engine warning light nor the particulate filter warning light is illuminated. It's simply the constant regenerative braking behavior, 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 far too high. I am confident that this is the reason for the seemingly endless regeneration.

The differential pressure sensor is not very expensive and can be replaced very quickly.
Easier than inspecting exhaust systems, tailpipes, etc. You might also have accidentally sat on something and crushed an exhaust pipe.

I can't help you with that; just check the exhaust system yourself. You might have installed separators in the exhaust system to allow for 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 mufflers with broken internal components, which means the exhaust flow can be significantly restricted.