bora TDI engine stalls while driving

'Hi, hello. I've been having problems with my Bora TDI, manufactured in 1999, with 90 horsepower, for a few months. A few days ago, it simply stopped running while I was driving, and now it won't start at all. Three months ago, I had the same problem. I called roadside assistance, and they said the 109 relay was broken. I replaced it, and since then, I've installed three new 109 relays, but the problem keeps recurring.'
'Since Thursday, the car has been at the VW dealership. They initially thought the problem was a faulty control unit, so they ordered a new one and installed it, but the same error persisted. They said the two control units weren't communicating with each other. Then, about two hours later, the master mechanic called me and said they had done a lot of testing and that there's an electrical component in the instrument cluster, and they suspect it's causing the problem about 90% of the time. It costs around 250 euros. Could it be that component? Has anyone else experienced this?'

asillisa wrote:

... and since there's an electrical component in the instrument cluster, and we suspect it's the cause of the problem 90% of the time, it costs around 250 euros. Could it be due to that component? Has anyone else experienced this before?

No, that can't be right. There is a part of the immobilizer system in the speedometer, that's correct. But even if you remove the speedometer, the engine won't turn off. It won't start without the speedometer connected, but once it's running, it doesn't matter whether the speedometer is connected or not.

By the way, something else I remembered: I once tried bridging the pins with a cable where the 109 relay is located, and even then, the preheating indicator didn't appear, so there's no voltage getting to the 109 relay.

Okay, here's the translation:

'So, I got my car back today after two weeks because VW couldn't supply a combination instrument. I paid for the repair. I drove for half an hour, and then the same problem happened again: the car is making a sound but won't start. From the outside, it looks like the 109 relay might be defective. The preheating indicator light on the dashboard isn't coming on, or it comes on for a few minutes, the engine starts briefly, then shuts off again, and the preheating indicator light goes out. What could be the cause?'

Replace the power supply relay... I don't have the socket or part number in stock at the moment... but this is a known issue... 98/99/00...

mechanics77 wrote:

Replace the power supply relay... I unfortunately don't have the socket or part number in stock at the moment... but it's a known problem... 98/99/00...

This is the 109th .
I also think that approach is correct, but since the relay has been replaced multiple times,
It seems the only way to trace the wiring is by using a continuity tester, starting from the fuse and following the 109-gauge wire.
Until the MSTG.

Best regards,
Micha

It seems like the engine doesn't start when it's warm.

Whatever it is,
It is not a warm-start problem in the same way as it is with many 110PS TDI engines.
(After 8-10 seconds of cranking, it finally starts).
To really make progress, you'd need a laptop and VCDS, and then you could check things out.
how the involved control units behave in the event of a failed start.
(If the pre-illumination light remains on, it could be, for example, that the MSTG is not responding.)
because it is not properly maintained.

Best regards,
Micha

Okay, so I called customer service, and they said the control unit is faulty. They removed the control unit, and if you bend the circuit board a little, it doesn't respond. Could it be related to an OBD tuning job that was done about a year ago?

What is the part number for the MSTG?

VW part number: 038906018AE
bosch part number: 0281001851

The "tuner" either lied to you (and you're not getting any extra power), or they're wearing...
"Blame for the mess (assuming it's really the MSTG; I'm surprised that..."
(A specialized workshop opened the part).
The 018AE is an MSA15.7 and cannot be programmed via OBD.
The tuning process involves soldering the memory modules, which can sometimes lead to problems.

Best regards,
Micha

Yes, but I've been driving this vehicle for about 9 months, so shouldn't it have broken down by now?

No.
Okay, gib mir den deutschen Text.
If there's too much heat during soldering, the pads can detach from the circuit board; then...
The vibrations from the engine eventually cause the circuit board to break.
Then, depending on the temperature, her mood, and the amount of coffee in the machine, she would sometimes interact with it.
(Engine running) or not, as the case may be.

Best regards,
Micha

Do other engine control units (ECUs) fit in the car, such as those from the 110 hp engine or other 90 hp engines, etc.?
'if so, what should be considered?'

Buy the same VAG part number, and you'll be happy.

If you can't find anything, the part number 038906018AE is located in my cabinet.

Best regards, Rainer.