Emergency Program: Quick & Easy Solutions

Hello.

My A3 TDI (ASV) went into limp mode on Monday while accelerating in 3rd gear (starting at approximately 3000 RPM). After restarting, everything was normal again. When I checked with VAG-Com, I received the following error message:

1. DTCs Found:
17965 - Charge Pressure Control: Positive Deviation.
35-00 - -

Then I checked the forum, and I mainly found the following source of errors there:

N75, vacuum hoses, mass airflow sensor, turbocharger.

What is an N75 (perhaps the vacuum pump on the camshaft?) and how would you proceed with troubleshooting it? Please avoid using too many technical terms, and if possible, provide a more detailed explanation (perhaps with pictures) .

As mentioned above, I can use VAG-Com for searching.

Best regards, Hüso.

Hello, the N75 is a solenoid valve.
I guess that's the valve for the turbocharger pressure regulation.

Where is it located, what does it look like, and how can I test if it's still in good condition?

hueso wrote:

Where is it located, or what does it look like, and how can I test to see if it's still okay?

Hi.

First and foremost, always follow the hoses.

http://www.dieselschrauber.de/tdischlauch.html

-> VTG Loader

The information is great - I should have been able to find it myself .

I just read that it could also be a 'leak between the turbocharger and the engine (charge air path).' This is particularly interesting to me because one of the turbocharger screws was once resting on my lower engine cover, and I tightened it without using a torque wrench.

Could I have damaged a seal in the process? Does anyone know the torque specifications for the mounting screws?

Best regards, Hüso.

Hi,

hueso wrote:

I just read that it could also be "a leak between the turbocharger and the engine (in the charge air path)".

Strange, where did you find that? I find it unlikely that this would cause the boost pressure to become high.

Quote:

This is particularly interesting to me because one of the turbo screws was resting on my lower engine cover, and I simply tightened it without applying any torque. Could it be that I damaged a seal in the process? Does anyone know the torque specifications for the mounting screws?

Do you mean the connection between the turbocharger's compressor housing and the turbocharger's center housing?
I'm not sure if there's a seal there, but if there is a leak, the boost pressure shouldn't be too high.

Best regards, Rainer.

Sorry, you're right - that's error 17964: Tolerance exceeded.
It can't be happening to me .

I will check the errors described in the information about the tax pneumatic system tonight. Let's see if I can figure anything out.

Best regards, Hüso.

Hooray, I know what an N75 looks like .

Yesterday, I wanted to check the charge air cooler and try to vacuum the vacuum hose. However, it wasn't easy to see the charge air cooler from above. I didn't try accessing it from below (I didn't have time) - is it easier to reach it from below, or do I need to remove something from above?

Best regards, Hüso.

Hi,

Okay, so if I remove the sound insulation cover from the top of the engine, I can see the turbocharger housing and linkage from above with a little maneuvering.
You can also manually reach down from above and check as long as the engine is still cold .
You can obviously see it better from below.

Best regards, Rainer.

My car has already clocked 100,000 km. And now I'm having the same problem as Hueso.
At 160 km/h, the engine switches to emergency mode. The error code is the same as with 'hueso': excessive boost pressure.
Huso: Have you fixed the problem yet? If so, please tell me what was wrong.

Best regards, Chris.

No, I haven't had the time yet, and it's still too wet for me to get under the car.

Today, I logged the boost pressure behavior. I accelerated in 4th gear. The target value settled around 1 bar, but the actual value remained constant at 1.5 bar until the emergency program activated at approximately 2800 RPM.

I'll probably start working on it this weekend - let's see what it is!

Best regards, Hüso.

Quite likely one of the following causes:
- VTG (Variable Turbine Geometry) - The adjustment mechanism is either jammed internally (due to soot, bent guide vanes caused by rust particles ejected from the turbine wheel), or externally (at the shaft where the adjustment lever enters the turbocharger housing, or in the vacuum actuator).
- Faulty boost pressure control solenoid valve.
- The ventilation hose of the vacuum system to the air filter box is clogged.

Best regards, Rainer.

I wanted to check the charging socket and the charger first, as there seemed to be some difficulty adjusting them.

I'm wondering if I should check the solenoid valve first. Is there a simple way to do that? I seem to recall reading something about swapping the solenoid valve from the turbo with the one from the EGR system – do I also need to swap the connections? Probably, right? What else should I consider when replacing it?

First, I will check the hose from the air filter housing.

Best regards, Hüso.

hueso wrote:

I'm wondering if I should check the solenoid valve first. Is there a simple method for that? I once read something about simply swapping the solenoid valve from the turbo with the solenoid valve from the EGR system - do I also need to swap the connections - probably, right? What else should I consider when doing the swap?

Hi.

Simply plug it in directly. The characteristic behavior might seem a bit unusual, but the basic function should still work (assuming everything else is okay).

I've decided to dedicate myself to my baby after all.

1. The ventilation hose in the vacuum system leading to the air filter housing was not blocked.

2. Then I checked the VTG (Variable Turbine Geometry) adjustment. The engine was off - I hope that's correct? So, I applied suction to the vacuum hose, and the adjustment moved with a slight creaking sound. I can't say for sure if it was 1 cm, but I think it was. Everything seems to be sealing properly.

Now, it seems like the only thing left is the magnetic valve (N75). I'm going to try swapping it with the EGR valve in the next few days - hopefully, that's the problem.

Oh yes, and a big thank you to the forum and to everyone who helps out so wonderfully .

Best regards, Hüso.

I just replaced the solenoid valves, but unfortunately, it didn't help .

Should I now disconnect the pressure sensor on the turbo and try moving the valve back and forth, or does anyone know what else it could be?

Best regards, Hüso.