Seat Alhambra 2.0 TDI constantly regenerating

Good morning, everyone.

Unfortunately, my Seat Alhambra 7N, 2.0L TDI 150 HP, manufactured in 2017, has been experiencing significant problems for the past few weeks.

I've already tried to find a solution by looking at the posts here, but I'm having trouble interpreting the values.

The vehicle has approximately 150,000 km on the odometer and, in principle, continuously regenerates. When the vehicle is stopped, the fan continues to run at full power for 10 minutes, while during operation or after the ignition is started, it begins to regenerate. With the Carport SW (which I still had from previous vehicles), I can read all sorts of data, such as high temperatures in the filter, load limits, and pressure values from the differential pressure sensor, but I can't properly interpret this data or draw the correct conclusions.

Could you please take a look at the attached logs and perhaps offer some advice on how I should proceed? That would be really great.

Thank you very much.
Best regards, Knut.

Hello,

Please upload the logs. If the regeneration process always starts but never completes, please check the ash mass/ash volume in the DPF (which can be read from the ECU's measured values) and consider whether the regeneration process itself is producing so much soot that the DPF never empties.
For example, in the case of a leak in the charge air cooler system.

See:
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and
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Comparison values for ash content:
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Good luck, Rainer.

Hello Rainer,

Thank you for your quick response.

I've attached the logs to the original post again.
As I understand it, the vehicle is able to complete the regeneration process. However, the next regeneration process starts very quickly again - for weeks now, it has essentially been impossible to turn off the vehicle without the fan continuing to run at full power for approximately 10 minutes.

Greetings,
Knut.

Take a look inside the SCR compartment with an endoscope, or simply tap on it. Most likely, the SCR (Silicon Controlled Rectifier) in the cat (likely referring to a catalytic converter) is broken or fused.

Thank you for the information.

Is the assumption that the SCR is defective based on the log data?

Sorry for the silly question, but basically, is it about using the endoscope through the exhaust pipe towards the SCR catalyst? I have an endoscope available with the appropriate length.

Should I read out any more sensors and provide the log file?

"By the way, I didn't receive any warning lights, and the engine control unit's error memory doesn't indicate any faults."

Thank you for your support!
Knut.

Remove the AdBlue injector and then use an endoscope to inspect it, but there's a swirl plate in front of it.
Most of the time, you can hear it just by tapping. I've experienced this multiple times.

I haven't looked at the log yet, but if the Russian mass is increasing extremely rapidly, then it's probably a broken SCR catalyst.

Okay, thank you!

Okay, I'll take another, more detailed look at the Russian dough using the log.

Hello everyone,

This morning, I conducted and recorded several test drives.

What I currently believe to be true:

- The car does not regenerate continuously (as I had previously assumed). While the amount of soot is constantly increasing, I can see in the logs that this is happening slowly. For example, the last regeneration took place approximately 260 km ago, and since then, 18 liters of diesel have been consumed. While there is a significant difference between the measured soot mass and the calculated value (11g versus 19g), it is still below the threshold for field generation.

- During the logging process, the fan then turned back on. I added a marker (1) to the log file, which can be seen in the log. In this log, I recorded data from virtually all of the MSG's sensors in an attempt to identify any deviations. Unfortunately, I haven't been able to identify it myself yet.

- As I mentioned, the fan was running at full speed. The start-stop system was still working, and after I turned off the ignition, the fan continued to run at full speed for about 5 minutes (it sounds like a helicopter taking off).

- The water temperature remained constant at 90 degrees Celsius during the journey, and the oil temperature was between 80 and 100 degrees Celsius.

I am attaching the log file for this trip. As I mentioned, just before marker 1, the fan turned on at full speed.
I'm sorry that this log is so disorganized, but I just wanted to capture as much information as possible.

I would be very grateful for any tips or suggestions you might have for further troubleshooting!

Greetings and thank you .

Hi,

The CSV file is from Carport, and when I open it in LibreOffice, I notice that a lot of different things are being logged.
This depends on the sampling rate of the individual values, and it's usually not a good approach because with too low a sampling rate, the reliability of the results eventually approaches zero.

Not only useful for VCDS:
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Your exhaust gas temperature appears to be within the normal range for typical driving conditions, specifically before the turbocharger, at an engine speed above 2000 rpm, and under load (without thrust).
If the temperature exceeds 650°C, it will regenerate. There's probably some bit somewhere that directly indicates this.

Perhaps one of the two fan speeds on the cooler fan is defective? P.S. In the extensive log file, I didn't find any coolant temperature readings; I may have overlooked it. What is she actually like?

Best regards, Rainer.

Hello Rainer,

Thank you for your quick reply.

Sorry for this massive log file. I just looked at your link and will focus on the relevant data and format it accordingly in the future. I haven't really had much experience with log files yet.

I can't actually find the coolant temperature in this monstrosity either, but I'm going to take another drive and specifically track the coolant temperature and the exhaust temperature.

Best regards and thank you
Knut.

Hello Rainer,

I wrote a new log. During the ride just now, the fan didn't turn on.

I have been tracking the coolant temperature and the exhaust gas temperature. Sensor 1, which measures the exhaust gas temperature, is producing values that deviate significantly from those produced by sensors 2-4. Is that normal?

Best regards and thank you,
Knut.

Hello knuttutgut.

I'm experiencing a similar problem with my Seat Alhambra 2.0 TDI from 2016, with approximately 150,000 km on the odometer.
Have you found out any more about the error?
I've noticed that the error rarely or never occurs when the vehicle is towing a trailer.
The problem has existed for over a year (20,000 km).
"Only the smaller fan runs at full speed for about 1 minute."
after turning off the ignition. And also after the engine starts, and occasionally during driving.

Hoping for help soon.

Best regards, Stefan.