Emergency Mode: Faulty Control Unit, Dashboard Error

A week ago, I drove approximately 150 km in the morning. When I got home, the car sat for about an hour before my wife drove it to work. She immediately noticed that the engine speed went up to 2000 RPM when starting, as if someone was pressing the accelerator pedal. During her drive, she also noticed a loss of power. Since then, the car has only been running in "limp mode" and constantly. A diagnostic scan at VW revealed three error codes:

- Fuel shut-off valve.
- Engine control unit locked.
- Engine control unit (ECU) intermittently defective.

They didn't want to delete the error codes because it would make troubleshooting more difficult and the car might not start afterwards. Since I still have a warranty on the car, I unfortunately couldn't get to the dealer until today. Unfortunately, the diagnostic tester was broken only today. However, he told me that I should have the error codes cleared.

Tomorrow morning, I'm going to take my car to VW and have the error codes cleared. Is there anything that could go wrong? Is it actually a problem with the control unit, or could it be related to relay 109? I've read about that connection a few times before.

This is a Volkswagen Golf 3 TDI with 110 horsepower (AFN engine), 238,000 kilometers on the odometer, and a new mass airflow sensor.

Okay, I just went to the Volkswagen dealership and wanted them to clear the error codes. However, they couldn't do it because they weren't able to establish a connection to the control unit!

What's the problem this time? Is it a broken cable in the diagnostic wiring, or was it the incompetence of the VW trainee who initially thought the diagnostic connector was located near the hood release?

The mechanic came back out and asked if I had an original radio installed, because it could also be related to that... Or could the whole problem also be due to a faulty ignition switch? Because for about three weeks now, my radio sometimes doesn't turn off when I remove the key. If I press the ignition switch briefly, then it turns off.

That definitely sounds like an ignition switch. And it's also relatively inexpensive .

I would recommend getting it replaced. It's possible that you might not be able to remove the key later on... a friend of mine had to disconnect the battery to turn off their car because of this.

But it doesn't put the car into emergency mode, does it?

HI,

An unstable power supply can cause a computer (like the MSG) to do all sorts of things, often resulting in extremely chaotic errors.

If you also suspect that something is wrong, address the issue first.

Best regards,

Jan.

P.S.: I would classify "sporadically defective" as a chaotic error... it's about as informative as saying "sporadically dead" .

Not directly. But it can, for example, temporarily cut off the power or simply reduce the voltage, etc.

And that's why the control unit (STG) malfunctions. Even if he shouldn't be responsible for all the errors, it should still be replaced because its other features can make troubleshooting more difficult.

edit: too late.

Okay, I just went to a different Volkswagen dealer. They immediately accessed the engine control unit (ECU) and cleared the error code. The car is now running normally again.

The data retrieval failed at the first dealer because the trainee was always entering code 17 (terminal block adapter) into the tester. That's why no connection could be established. Afterwards, the master technician wasn't interested in why it didn't work.

I only realized when I got home that the 17-slot terminal block was the wrong one.

But the mere fact that your radio doesn't always turn off would make me switch to a different one.

If you're driving home at night and suddenly all the lights go out and the engine stops, then you get annoyed again. And the switch won't fix itself automatically.

Yes, the switch will be replaced in the next few days. I believe it costs only €60 from Volkswagen for the complete replacement. The dealer where I bought the car probably offers it at a slightly lower price.

The car is back in limp mode! I drove home earlier, everything was normal. Then the car sat for an hour. Afterwards, I went to Dortmund, and again everything seemed fine, but the car only stood there for 5 minutes. When I started it up in Dortmund, the RPMs shot up again, and the car immediately went into limp mode. On Saturday, I'm taking it back to the dealer where I bought it; they need to check it out.

How does this relate to relay 109?

Hi,

Quote:

How does this relate to relay 109?

Repair your ignition switch!

The famous Relay 109 is connected to the power supply of the MSG, as is the ignition switch (not directly, but indirectly). A faulty power supply can easily explain your problem - so why bother troubleshooting Relay 109 when it's even known that the ignition switch has a defect?

Believe me, no one, not even a workshop, can help you effectively until an error that is very likely related to the problem is fixed.

Of course, you can now replace almost anything on the car, but that's a pointless waste of time and money.

Best regards,

January.

Okay, let's start from the beginning: The error message has been cleared, and after that, I drove home normally; the car had full power. When I got home, I left the car parked for an hour, so it cooled down again. After an hour, I drove back to Dortmund, and everything was normal again; the car had full power.

Okay, so in Dortmund I only parked the car for 5 minutes and then started it again while it was still warm. Now, when I start it, the RPM goes up to 2000, and the car immediately goes into limp mode.

So, the engine speed only goes up to 2000 RPM when starting a warm engine; afterwards, it enters limp mode. When the engine is cold, it starts normally without an increased idle speed. However, limp mode is still active, because once it's engaged, it won't go away unless the error memory is cleared. What could be causing this?

I won't be able to read it again until tomorrow. Let's see what it says then.

I doubt you'll get much help here if you don't fix the known defects.
It's possible that a completely different set of errors will appear after the repair (which is very likely), and then you can properly investigate the issue.

My child experiences the exact same symptoms every few years for about one to two weeks.
Same error entries.
It only went into emergency mode for me when it was started while still warm.
100% reproducible.
It walked away on its own.

Consider getting an OBD2 cable with VAG-COM software. You probably already have a laptop.
Should be a must-have in every household .

The car is running again. Only relay 109 was replaced and the error memory was cleared.