Car Won't Start: Troubleshooting & Fixes

Hi!

"Today, after a short drive and turning off the engine, my A3 AHF wouldn't start. There were no warning lights on the dashboard, and the error memory is empty. After a few attempts, it started again without any issues. The mechanic says that, based on experience, it's likely the power supply relay for the engine. Could that be the problem? Where is it located? Where can I get a replacement relay?"

Best regards,
Uwe.

... Search using (Relay 109)...

... does not produce the desired result. Relay 109 is causing error entries, but I have no...

If you use the forum's search function, you will find, for example:

/viewtopic.php?t=147&highlight=relais+109

/viewtopic.php?t=149&highlight=relais+109

Therefore, I wrote "Use search"!!!

There's already been so much written about it that I don't want to repeat it here.

Hi!

Thank you for your efforts. I have already found those entries, but they describe relay 109, not MY problem (the engine doesn't start, no error code). The workshop wanted to replace the relay (50 euros) without being sure that it was the cause. That's why I asked: could it be that? What are typical and possible sources of error?

Best regards,
Uwe

Hello Uwe,

Relay 109 doesn't cost 50 euros; at the friendly local store, it's just under 20 DEM (or were they 20 euros??) directly from the parts department. That's at least my personal experience.

You can remove the relay, open the casing, and then look for cold solder joints on the circuit board.

Best regards, Georg.

If you were to read the other entries carefully, you would surely have noticed that some people mention that their car wouldn't start, but then it starts again after it cools down.

If I remember correctly, that is exactly your error description.
If you put your thoughts together, you can even figure out the problem yourself. Your friend called it the "power supply relay." --- Where there's no voltage, there's no running motor --- that's just the way it is. A cold relay might still function, whereas a warm one might not.

It has even been read in various other posts that in the relay caused failures due to poor solder joints, and simply resoldering fixed the problem.

That was a summary of the common Relais 109 errors that have already been discussed in this forum X times.

Okay, next time, please read the posts carefully beforehand (not just the title), and then questions like that will become unnecessary.

Thank you for the clarification...

Uwe.

Hi Uwe,

You're quite experienced in the forum, aren't you? Surely you must remember various posts about release 109?
Okay, so don't be upset, it wasn't meant to be malicious...

Here's another tip that hasn't been discussed yet in this forum:
Try replacing the relay with a (thick) jumper wire. If the problem disappears, then you've found the cause.

Hi Bertil!

Actually, I didn't initially know that the power supply relay was relay 109.
In the researched posts, there are always errors in the memory (Michael: 8 errors!). Of course, that doesn't always have to be the case; in my case, there was nothing there. I'm not even concerned about the cost of a relay, whether it costs 10 DM or 50 euros. I've just experienced that these kinds of errors often lead to a chain reaction, and the error is very often not resolved with such a diagnosis. And that's exactly what I wanted to prevent.
Sure, to accurately analyze my problem, you need more information, a psychic – or this forum! Maybe someone else has experienced the exact same issue with the same car model, with the same mileage and driving style, and at the exact same location.
Okay, no problem. I'll bring along a piece of wire mesh fence starting tomorrow, and I'll continue using the old relay for now.

Best regards,
Uwe

Uwe wrote:

...In fact, I initially didn't know that the power supply relay was relay 109.

... okay, that wasn't mentioned anywhere.

Quote:

...The researched posts consistently contain errors in the memory (Michael: 8 errors!). ...

In my experience, error messages actually occur quite rarely.

Quote:

... I've only experienced that such errors often have far-reaching consequences, and that the error is very often not resolved with such a diagnosis. And that's exactly what I wanted to prevent. ...

That's already clear, and nobody wants to fix nonexistent errors that aren't actually there.

Quote:

... Sure, to accurately analyze my problem, you need more information, a psychic – or this forum! Maybe someone else has experienced the exact same issue with the same car model, with the same mileage and driving style, and at the exact same location.

Oh dear, you're probably going to have bad luck. If it really is the relay, it can happen at any time and with any TDI. The risk is higher with the older ones . A relay is a wear part, and after a certain number of switching cycles, the contacts can break.

Here's another tip:
If you're comfortable, you could open the relay and do a visual inspection. Often, bad or broken solder joints can be identified with the naked eye. While you're at it, you can also take a look at the contact tongues; if they are very black, I would recommend cleaning them.

Quote:

... Okay, no problem. I'll bring along a piece of wire mesh fence starting tomorrow, and I'll continue using the old relay for now. ...

... I think that's the most sensible solution...

Chain-link fence.
But the snapdragon bush is no longer included ?

Hi,

Here's a contribution from someone affected by the Relais 109 incident...

'I had the exact same problem: the car wouldn't start when it was warm (G3 AFN engine). I went to the dealership three times to have the error codes read, but they found nothing. The mechanic then said there were two possibilities: 1) have the entire car thoroughly checked, or 2) replace relay 109, as it's known to cause such issues. I chose option 2 because it was significantly cheaper (50 Deutschmarks).'
Unfortunately, it was even worse than before. Now, the car even started to shut off while driving . I can tell you, you make some good friends in rush hour. So, back to the workshop, and I told them to check the car. It turned out that the replaced relay was also defective . Since I couldn't find the invoice, I was unfortunately unable to prove that they had sold me the faulty part. Well, I guess I had to bite the bullet.
By the way, I opened both relays and couldn't find any cold solder joints or anything like that. They looked intact to me.

Best regards,
René K.

zzzZZ wrote:

... By the way, I opened both relays and couldn't find any cold solder joints or anything like that. They looked intact to me. ...

Hi René,

What were the contacts like?

Otherwise, it's a real horror story!!!

Hello everyone.
I just read about all your troubles.
I would like to add a piece of advice based on my own experience:

I actually experienced similar symptoms, which almost drove me crazy.
The car stalls while driving, only starts when cold, and has unpredictable starting problems when warm.

After A VERY LONG SEARCH and some luck.
I then found a COLD JOINT in the immobilizer system.
There is a complete entry about this issue in the error database.
/viewtopic.php?t=1278

Maybe you can find a solution with this.

Good luck and get well soon .