Error code P0299 - Turbocharger/Supercharger Underboost Condition.

Hello community,

I'm new here and signed up because of the problem described in the title.
I drive a Seat Leon 1.8 TSI (model year 2010) with approximately 95,000 km total mileage, of which 10,000 km were driven with a software optimization. Today, I accidentally discovered the error code "P0299" in the engine control unit's fault memory.

"During the drive, I didn't notice anything unusual, so I assumed it was just a sporadic issue. The engine didn't go into limp mode, and the check engine light on the instrument panel didn't come on."

Due to the chip tuning, I decided to log the boost pressure during a full-throttle acceleration. You can find the log file in the attachment.
Could the issue be a worn-out boost valve due to the increased boost pressure? I had previously felt a gradual loss of power at higher RPMs, but I thought it was temperature-related.

Best regards,
Dennis.

This is not uncommon. The load data on these devices are often determined through the television, and not necessarily based on a target/actual map or comparison.

Hi,

Thanks in advance for your reply. I'm not an expert, and I suspect that your abbreviation "TV" refers to the duty cycle of the charge pressure control valve?

Unfortunately, today I was only able to check the valve control; a continuity test was not possible due to the lack of a lift platform. At least it did click .

Ich hab auch nochmals eine Logfahrt gemacht, der Fehler trat nach Löschen nicht mehr auf, trotz allem kommt mir die Beschleunigung sehr wellig und unkonstant vor. Im Anhang noch der Auszug aus dem Fehlerspeicher und die neue Log-Datei (3. Sure, here is the translation of the text from German to English:

"Gang."

Greetings.
Dennis.

The pressure appears to be consistently within the normal range and looks fine.
Check the rail pressure, as well as the low pressure at the fuel pump.

Unfortunately, I couldn't find the fuel pump pressure reading. In which diagnostic trouble code (DTC) module is it typically displayed?

I was able to record the rail pressure, which seemed normal. Unfortunately, I forgot to note down the RPM, but that's not a big deal.
In addition to the boost pressure, I also recorded the function of the N75 valve, which seems to be working as it should.

The error is no longer appearing... Maybe it was just a false alarm .

I believe that low pressure is also present in the 103...106 and 140 series of Mercedes-Benz vehicles.

Hi,

I have now decided to stop using the low-pressure system log because the error has not occurred again so far.

Nevertheless, I proactively exchanged the SUV. I decided on the GFB DV+. For those who are interested:

Installing the K03 turbocharger without a lift is quite manageable if you remove the right front wheel and the wheel well; this gives you a clear view directly onto the SUV.
The result after removing the original part was that it was already partially porous, but without any obvious cracks. Nevertheless, the new part had a significant effect: my turbo whistle completely disappeared under full load. Therefore, I suspect that the membrane was indeed slightly leaky.

Best regards and thank you for the help .

Thank you for the feedback .

It would be helpful if you could let us know later whether the wastegate valve was actually the cause. We'll keep this thread open in the meantime. Thank you.

Hi,

The SUV was the problem. Yesterday, I drove a longer distance, including on the highway, and the car drives smoothly again.

There are no more errors in the memory.

Greetings.

Ok... Thank you .



Edit: Moved back here for editing upon request .

Thank you very much!

I initially thought the problem had been fixed. However, after several more trips, the error reappeared. I deleted everything again and tried to reproduce it.

Full throttle from the lowest RPM to the rev limiter in second gear --> no problem.
Full throttle from the lowest RPM to the rev limiter in 3rd gear --> no issues.
Full throttle from the lowest RPM to the rev limiter in 4th gear --> no issues.

I was able to reproduce it by flooring the accelerator and shifting from second gear directly into fourth gear.

In the attachment, you will find both the log file from when the error occurred and the error memory entry.

I've already replaced the N75 sensor, so it shouldn't be the problem. The hose to the intercooler seemed to be in good condition.

Are there any other possible solutions, or do you think the problem lies with the software, even though it has been working flawlessly for over 10,000 kilometers?

Greetings.

He never achieves the target boost pressure.

Is the wastegate stuck?

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hi,

Thank you for the response. How can I check this while it's installed, and are there any reference values that a non-expert like me can use to assess it?

Greetings.

MisterD wrote:

Hi, Thank you for the response. How can I check this while it's installed, and are there any reference values that a non-expert like me can use to assess it? Greetings

Set Point: Boost Pressure - (specified)
Set Point: Boost Pressure - (target/desired)

Best regards, Rainer.

Okay, I'll make sure to record that and upload it here when I have the chance.

Greetings.

Hello community,

Unfortunately, it's taken some time due to shift work and vacations, but today I was finally able to use my laptop with the car again.

During the initial scan, I noticed that the error in the engine control unit was no longer present. Over the past few weeks, I've driven over 4000 km, which seems to have been enough to reset the fault counter .

I still created a log of the boost pressure and can't find anything unusual there either. I'm starting to suspect that the problem might be in the software. What do you think? (Please ignore the last part, I accidentally recorded it again while decelerating.)

Greetings.