AD Blue Fehler immer wieder | Posts 16+

The cost spiral started as early as the second [item/phase/etc.]. SCR-Kat... since then, enough money has flowed to fix the problem.

Either educate yourself or go to someone who doesn't just mindlessly swap parts. X

I'm not in Munich.

Just a quick update: Besides my usual short commute to work, I drove 67 km (round trip) on the highway with my family today.

"On the way there, it immediately started regenerating; the SCR catalyst reached approximately 500°C, which we read live. Apparently, the crucial factor is the NOx conversion rate. At 96 km/h with cruise control, it was 0.67, which is about 67%. The efficiency threshold is usually around 30% (approximately 0.3). Is this normal?" I think that's quite a bit, still sufficient but not much.

On the return trip without regeneration, the SCR catalyst temperature was around 250-260°C, then at ~0.55, which is 55%. He also entered "SCR efficiency too low" somewhere in the diagnostic trouble code (DTC) log . No counter has been registered yet. What NOx emissions are you getting at around 100 km/h?
SCR valve activity initially at 5%, later decreasing to 0% and then increasing up to 15%.

Occasionally, my son mentioned that the NOx conversion rate dropped to 0.

Yes, the parts warehouse in Kassel has just postponed the delivery date of the SCR catalytic converter from November to December. I don't think they're making them anymore. I've been trying to get one since July.

Best regards, Thorsten.

Hello,
Is the AdBlue nozzle opened by pressure or by an electrical pulse?
Have you measured the pressure in the system, or just checked it via the PC? Are those 5 bar you mentioned also the target pressure? It seems unusual that the nozzles are spraying three distinct streams instead of producing a fine mist.
My suspicion is that the AdBlue is not being atomized sufficiently, and therefore the catalytic converter cannot convert the required amount of NOx.
This is just an idea and should be understood as a starting point for discussion.
Best regards.

Hello.
Yes, I tested the nozzle both inside and outside the vehicle.
The vehicle with the test program emitted a consistent clicking sound. That's all you could see or hear. She had it hanging down from the vehicle months ago during testing - three beams.

Pressure: I believe it should be 5000 hPa for all of them. Once, during a static pressure test, the line overheated, causing the substance to spray onto the floor, and the error message read "...reduction valve pressure too low," so I think the sensor is the problem.

Three beams: Yes, I created that using a compressor in the basement, and there was a fine rain of water falling from above. Whether it's correct or not... it's been replaced twice in the last two years, which seems rather unlikely.

I suspect that the NOx conversion may not have been sufficient with the used (original) catalytic converter, which was then sold and "repaired" cosmetically by the company "hübsch" and sold to me as refurbished. Anything is possible. Why would someone remove their catalytic converter unless it's due to an accident or defect? It's strange that the aftermarket catalytic converter from JMJ worked for two years, and then the "new" one failed so quickly. Yes, it could be AGR, but it could also be 37.5 other things.

"I think it would be helpful if someone could provide a log of typical values at speeds of 90 km/h and 100 km/h, indicating what values would be considered 'normal' at those speeds."
I can drive at approximately 95 km/h. Above 110 km/h, the NOx conversion rate drops from 0.5 to less than 0 (as indicated by the counter).

Thank you. Greetings.

Hello,

I would like to examine the values of the various temperature sensors in the exhaust system and compare them with a reference vehicle under different load conditions.

It's important that the engine control unit doesn't calculate with incorrect temperature values, otherwise the AdBlue dosage and other calculations will no longer be accurate.

The temperature before the catalytic converter is normally 150-200°C at idle, 600-700°C at full throttle, and up to 800°C during regeneration. Values obtained from estimations, intended only as a rough guideline for the order of magnitude, vary significantly depending on the specific medical condition.

The temperatures in/after the catalytic converter are significantly delayed and lower.

When the engine is cool, the displayed temperature should be approximately the ambient temperature (it doesn't matter if it's 5°C higher or lower).

The error entry in the Autoscan at the beginning of the topic must have occurred while the engine was warming up, correct?

Does the coolant thermostat work? Please ignore the AI-generated suggestions, as they are not very helpful for troubleshooting. Instead, read the coolant temperature from the engine control unit.

Are there any modifications or additions that can be made to affect the temperature behavior of the exhaust system?

Once, someone who thought they knew better installed an oil cooler in the wheel well of a T3 and then added so many dirt filters that it completely blocked the cooling.
And in my case, the body shop forgot to clip the air vent for the engine coolant cooler into place on the new bumper during a car repair.

Perhaps check the exhaust gas temperature when running at full throttle; it shouldn't exceed 60°C.

Best regards, Rainer.

Hello.
Everything on the VW is standard; I have never modified or changed anything on the aircraft itself.

Yesterday morning, I drove 25 kilometers on the highway to the club, and the temperature was around 4°C. I also logged the return trip. It's really tedious to select the values to measure in OBD Eleven because there are so many.

To me, it all seems plausible. I just don't have anything to compare it to.

Oh yes, on the way there, I logged the temperature of the fuel tank. It consistently remained at 3.9°C. When does it actually start heating up? Is it only at -11°C or something?

Thank you. Best regards.

Hello,

I was one of the people who responded to the thread creator's request on the TX board back then.

The original post also included a question about aftermarket SCR catalytic converters, and people's experiences with them.

Recently, a technical article appeared in the "Krafthand" magazine, which, coincidentally, also dealt with a Sharan model experiencing issues with its SCR system.

In essence:

SCR catalytic converters from aftermarket suppliers often have mixers that differ from the original design, which can result in the injected AdBlue not being distributed as intended.
These mixing/diffuser plates are patented in some cases and may not be reproduced by accessory manufacturers. So, always use genuine SCR catalytic converters, especially when dealing with unclear error patterns. Referring to the post in the "Krafthand" forum, even the supplier/manufacturer of aftermarket catalytic converters ultimately recommended using a genuine part.

Just a quick note on the side, and without questioning anything that has been said so far.

I found the mention of the temperature sensors particularly valuable, because the influence of these sensors is often underestimated. Age-related drift in these sensors can lead to values that, depending on the software, are processed or evaluated by the MSG as logically consistent, or are initially not flagged as implausible or erroneous.

Best regards and good luck with troubleshooting.

Hi,

Unfortunately, the logs aren't very informative. There are some things included that are useless, and other things that are missing.
First and foremost, the units. There are various measurement values that are sometimes expressed in mg/H, sometimes in g/s, etc. Without standardization, it's a guessing game as to what the measured value represents.

In most cases (with the exception of troubleshooting a sensor issue where the engine control unit is reporting an implausible signal), raw voltage readings from sensors are useless.
With a pressure sensor, you want to display the pressure in units like mbar, bar, hPa, etc., not just a raw number like "1234".

Check the temperatures of the various sensors when the engine is cool. This includes the coolant, intake air, pre-turbo, pre-catalytic converter, and inside the catalytic converter, etc. Take a sheet of paper and write something down.
I've looked at the columns with the values in your logs, and I think there are still quite a few temperature readings missing.

Then, after 1-2 minutes of idling with the engine running hot.

And ideally, it would have been logged with maximum detail. Engine speed and throttle position were added, so you know what the operator did.

Of course, independent thinking is also allowed. For example, if the exhaust temperature before the turbocharger doesn't exceed 400°C when running at full throttle and 4000 rpm, something might be wrong.

Best regards, Rainer.

Hello, yes, I know, I just picked something at random that came to mind. The output format of vcds, or the .csv file, is a disaster. It uses periods instead of commas, and everything is all jumbled up... it's much easier to analyze with OBD Eleven. Maybe I need to adjust something somewhere, I'll see. That's also why the units are missing; they were displayed, but they're always the same units. It's not measured in square feet times inches.

Which values/IDs are of interest? And then, what driving profile?
I'm planning to replace the fuel injector again this weekend. It's a quick job to replace it with a new one from Bosch. By the way, this time the seal is made of a metal shim, which is different from the previous design with the sealing ring. It's quite fiddly, you'll practically need three hands to do it.

Greetings.

No, the CSV file isn't a disaster; the majority of people are simply too clueless to understand the file format, which can even be viewed in a simple text editor.

Excel is stupid when it comes to file imports, just like almost all other Microsoft products. Local language settings should not be a factor during data import.

If you use LibreOffice, things will go smoothly in your life. VCDS users should use KDataScope.

The units are typically specified by VCDS. Please format the data correctly for the CSV file. I don't know your import format.

It's also completely useless to take an Excel file where the overly simplistic Winzigweich product interprets something as something else. Just take the raw CSV file; life can be that simple.

Quote:

Which values / IDs are of interest? And then, what driving profile?

I would like to compare different driving conditions with good and bad SCR efficiency, taking into account the target vs. actual EGR values, engine speed, and various exhaust gas temperatures.

Quote:

Check the temperatures of the various sensors when the engine is cool. This includes the coolant, intake air, pre-turbo, pre-catalytic converter, and inside the catalytic converter, etc. Take a sheet of paper and write something down. I've looked at the columns with the values in your logs, and I think there are still quite a few temperature readings missing. Then, after 1-2 minutes of idling with the engine running hot. And ideally, it would have been logged with maximum detail. Combining engine speed and accelerator pedal position will tell you what the operator was doing. X Thinking for yourself is, of course, also allowed. For example, if the exhaust temperature before the turbocharger doesn't exceed 400°C when running at full throttle and 4000 rpm, something might not be right.

How many more times do I have to repeat myself?

I find it unwise to pick up the wrench again without having ensured that what was said has been understood and assessed.

With your approach, you're playing a better game of lottery than you would with split roulette; if you win, you can buy yourself a new car without any defects.

Hello, I've recorded some data, but I couldn't find any information on exhaust gas temperatures. Maybe there's more to see. I drove fairly consistently. At the end, I accelerated quite sharply once. I still need to take care of the issue with the low temperatures.

Best regards, Thorsten.

Quote:

In the end, I accelerated properly once.

7s Gaspeal position 77%?

It's possible that the driving style is so conservative that the SCR catalyst doesn't reach its operating temperature. Again, please check the temperatures.
Also, whether anything has evaporated from any of the attachments (aluminum heat shield, plastic cladding, underbody panel, etc.), which could cause the entire system to be cooled too much by the airflow and never reach operating temperature.

dieselschrauber wrote:

Quote: In the end, I accelerated properly once. 7s Gaspeal position 77%? Yes, I thought that would be enough to evaluate things like the AGR rate, etc. It's possible that the driving style is so conservative that the SCR catalyst doesn't reach its operating temperature. Again, please check the temperatures. Also, whether anything has evaporated from any of the attachments (aluminum heat shield, plastic cladding, underbody panel, etc.), which could cause the entire system to be cooled too much by the airflow and never reach operating temperature.

Yes, as I described before. I've already figured out that it's not achieving the efficiency - no, better said, the NOx conversion rate (which is crucial). The (regular) test starts at approximately 280°C. If it fails, or if the value is below 0.3, the SCR efficiency error occurs. It counts this 20 times, and then I get the error message. That's exactly what I'm trying to avoid right now. This means running the SCR efficiency test, and if it fails, either leave it as is or buy a new catalytic converter. I've already finished the game.

Does the catalytic converter need to be hot for the EGR system to function, or is it sufficient if I drive with 100% partial throttle for a certain period of time?
Ah yes, the original cat is still not available for delivery.

Best regards, Thorsten.

Quote:

I have already figured out that he no longer achieves the efficiency - no, better, the NOx conversion rate (which is crucial). The (regular) test starts at approximately 280°C; if it fails, or if the value is below 0.3, the SCR efficiency error occurs. I mean, he counts it 20 times, and then I get the counter with the familiar display. Exactly what (I) need to avoid right now.

Okay, but debugging and verifying whether the error still occurs without the relevant conditions will not be successful.

You also can't tell if someone can swim if you watch them flailing their arms and legs on the grass.
To do that, you have to go into the water, and then you could potentially drown.

If the test is performed at 280°C, it's possible that a sensor might read 280°C even though the actual temperature is only 240°C, and in that case, the chemical plant would obviously not function correctly.

That's why I have repeatedly emphasized the importance of verifying the accuracy (of all!) temperature readings.

dieselschrauber wrote:

Quote: I have already figured out that he no longer achieves the efficiency - no, better, the NOx conversion rate (which is crucial). The (regular) test starts at approximately 280°C; if it fails, or if the value is below 0.3, the SCR efficiency error occurs. I mean, he counts it 20 times, and then I get the counter with the familiar display. Exactly what (I) need to avoid right now. Okay, but debugging and verifying whether the error still occurs without the relevant conditions will not be successful. You also can't tell if someone can swim if you watch them flailing their arms and legs on the grass. To do that, you have to go into the water, and then you could potentially drown. If the test is performed at 280°C, it's possible that a sensor might read 280°C even though the actual temperature is only 240°C, and in that case, the chemical plant would obviously not function correctly. That's why I have repeatedly emphasized the importance of verifying the accuracy (of all!) temperature readings.

Okay, here are some exhaust sensors that I found. I started the measurement before the engine started. To me, it all seems quite plausible.

Quote:

Current temperature in the NOx reduction catalyst: --- 25 25 25 25 25 25 25 1.5 1.5 1.5 1.5 1.5 1.5

Here's the first strange thing: why 25°C specifically?

It looks like a replacement part to me, so I would check to see if other vehicles with the same engine exhibit the same behavior.

Ideally, the problem would be a broken cable or a loose connection to this sensor, or a sensor defect. However, in such cases, a corresponding error message should ideally appear.

Perhaps someone from the forum has already looked at this or can comment on the behavior. For me, it's not plausible why a temperature that is initially too high is displayed.

Best regards, Rainer.