ECU Fault 31-10: Interruption Error Explained

Hi everyone,

VAG-COM reports:

Control unit part number: 028 906 021 AT.
Component and/or version: 00SG 0805
Encoding: 00002
Workshop code: WSC 05311.
1 error code found.
65535 - Control unit defective.
31-10 - Intermittent interruption/short circuit to ground - Occasional.

I found the error code 65535, which indicates a problem with the J248 (likely the control unit), great. The car is running relatively smoothly otherwise. Does the '31-10' reading perhaps reveal more about where there's an interruption or a short circuit to ground?
What other way is there to pinpoint what's not working correctly? I'd prefer to avoid taking the control unit out and inspecting it internally.

1996 Volkswagen Passat TDI 1Z.

cu, bogi

If your car drives well, why should you care about what's written in the registration papers?
Do you have chip tuning? If so, you've probably seen this message before, but if everything is okay, then what's the problem?

Hi,

I also had this error once on my car . Ultimately, it was due to VAG-COM (the error descriptions were shifted relative to the codes). Unfortunately, I don't know why that happened. Your control unit is probably not broken; just ignore it.

haehnlein wrote:

Unfortunately, I don't know why this was the case.

U. Ross has implemented such malicious features to make it more difficult to crack the software, which I certainly don't want to imply you would do.

65535 means 'control unit defective.' Nothing is shifted or out of place.

And if you think it's mean to slightly alter the text when I discover that someone has cracked my software, you have no idea what I could do if I were truly mean!

-Uwe-

I'm also familiar with this error from my Golf. In my opinion, it doesn't originate from the software itself, but rather is a result of hardware problems combined with VCDS (formerly VAG-COM) settings!

What other symptoms are there besides the error message? Are there any short bursts of exhaust and black smoke when starting up?

take a look here:

Okay, I understand. Please provide the German text you want me to translate into English. I will only provide the translation.

You should probably just ignore the error message; it occasionally appears even on devices at Volkswagen. As long as everything is running normally, most people wouldn't think to do anything about it.

Hello,

How did you resolve your issue? I'm experiencing the same error message, but with a significant performance loss.
In addition, there is also the pressure difference in the intake manifold control system.
I'm unsure whether I need a new control unit.


Best regards from Mulag.

In my opinion, I don't think your steering system is defective! I would just ignore it for now.
Address the other problems; they are the cause of your performance decline.

Please use the search function; you'll definitely find enough information about supercharger pressure regulation differential!

Okay, so I've replaced the hoses, renewed the boost pressure control valve, and checked the turbocharger's key points (full intake manifold pressure going to the wastegate: result is a maximum of 0.6 bar boost pressure, with no regulation at all: maximum pressure is about 1.2 bar - which should also be okay, right?).
Despite this, the system goes into emergency mode. Does corrosion also cause the mechanical components (lever mechanism) of the pressure sensor to seize up on the wastegate?
What might I have overlooked?

Best regards from Mulag.

P.S.: It has a two-cylinder boxer diesel engine without all that unnecessary fancy stuff.

What about the MKB? Are you going to reveal its secrets too?

If it's a 1Z (signature), then without a chip, the pressure of 1.2 bar (relative pressure) is far too high.

Please excuse my incomplete information. The engine code is 1Z. The 1.2 bar boost pressure only occurs when I override the boost control system. This means there's no pressure being applied to the pressure sensor from the turbocharger (I briefly disconnected the hose leading to the pressure sensor, just for a moment to avoid damaging the engine). Based on this, I believe the turbo itself is okay. Since the boost pressure is limited to 0.6 bar when I apply full intake manifold pressure to the pressure sensor, and based on everything I've read in the forum, I assume that the turbocharger and pressure sensor are okay (at least in terms of their basic functionality). If the engine control unit goes into limp mode, the boost pressure is also limited to 0.6 bar.

Best regards from Holger.

And what about the maximum boost pressure when the engine is not in limp mode? It should then be around 0.9 bar.

The pressure is around 0.9 bar. I also had it electronically checked by a friend who brought over the VW diagnostic tool (of course, that displays 1.9 bar because it shows the absolute pressure). Unfortunately, I don't have any log data from the drive. It tends to go into limp mode relatively quickly, and the warmer the engine is, the faster it happens.

Yesterday, I applied WD-40 to the linkage of the wastegate control again. Additionally, I checked the tightness of the pressure sensor by introducing external air (0.6 bar) and re-verified all the control lines that I had already replaced (better safe than sorry). The pressure sensor is tight. I also observed whether the linkage moves (approximately 3-5 mm of travel). For comparison, I visually inspected a Golf that I have as a loaner car (with an AHU engine), and it looks very similar.

Could it be that the wastegate has an internal defect, or is it the control unit?

Sure, here is the translation of the text from German to English:

"Hi,"

It is also possible that the solenoid valve controlling the pressure sensor may occasionally "stick".
Just try swapping them out for a moment (e.g., with the one for the EGR valve).

Best regards, Rainer.

Hello Rainer,

I swapped that out first. It performed worse than the diesel itself, and...
'I've driven about 250,000 km, and I thought that spending around 30€ wouldn't hurt. I'm just assuming the new part is okay. The question now is whether I should send the control unit to a specialist for inspection to be absolutely sure. Of course, 500€ is not an insignificant amount. The remaining possibilities, in my opinion, are either the control unit or the turbo (or perhaps the wastegate system, since I can't repair anything myself on that). I don't think the intercooler will leak, right? I've already removed all the hoses connected to and from the intercooler, and nothing seemed amiss.'


Best regards, Holger.