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I have purchased a 2012 Audi A4 off a dealer. Within 2 weeks I have had and engine light come on the dash along with a message reading "Start-Stop system: system fault. Function unavailable" below is a list of symptoms the car is showing.
- Solid engine light
- Auto start-Stop message on dash on car start
- When Idling the revs will pulse slightly up and down (normally sitting around 800rpm, pulsing up to 1000rpm for about a second)
- Whenever the revs pulse up the gear on the dash will disappear then come back (can be seen in attached video above)
- Driving downhill taking foot off accelerator will also cause the gear on the dash to disappear
- I'm not 100% sure if this happened but I remember the gears changing rapidly (about 4 changes in a few seconds) when accelerating from traffic lights
I am taking the car back to the dealer to sort out the problem but it has come up a few times now. I have taken the car back once before and they removed the engine light then there was no problems for just over a week.
Has anyone else had the same issues as me and might know what the problem is as I'm worried the dealer will just remove the problem again which will last another week.
If you never found out the actual DTC(s), then you have no idea what the car is actually having a problem with. Which means there's no way to guess what or why it's recurring or if the recurrence is reasonable.
That output is painful. Ross-Tech VCDS is pretty much the expected standard of output, anything less is less. OBDeleven is not bad, but it takes more manual work to compile the log text to the same level. The tool you used, well, let's see what we can dig out of it.
ECU: 03. ABS control unit
Audi: C107701: ABS return flow pump
Electrical error
Ok, but I'm not really sure what to make of it. Never seen that before, and a search turns up that as more an A3 error code than the Audi platforms, where 00301 would be expected. In either case, If it thinks there's an actual electrical issue with one of the hydraulic fluid pumps inside the ABS hydraulic unit, you're probably looking at having to replace the unit. But maybe it just means there was a failure of electricity delivery. There are a lot of fuses that feed the J104 ABS unit. You're in a right hand drive country though, so it's a different set of fuses.
In the fuse panel on the positive post of the battery, you should have an 80A fuse in position 3, this feeds the three fuses (S123, S124, S137) that feed the ABS control module. So you want to check this one first.
Then the three fuses themselves are behind the passenger side kick panel at the base of the passenger side A-pillar. A 40A, 25A, and 10A at the top of the connector station there.
If there's more to it than a fuse, you're going to have to determine what exactly that that code is trying to say. There is that big 37-pin plug on the front of the J104.
If the dealer has had to interact with this issue before, ask them what they think it is and what they are doing. Maybe that'll give you some indication of what is not working.
Then there's a number of "lost communication with the TCM (transmission control unit)". The output has some entry for the TCM, but "Supply voltage at rear passenger side ventilation control unit; Supply voltage for the rear seat fan on the passenger side"? Yeah, ok. The TCM talks to the rest of the car through a 14-pin plug, iirc. Is there an issue with that plug? Are they finding ATF seepage along the pins? Have they just been cleaning the plug off and putting it back? If the dealership has been working with this issue again and again, what are they doing?
The rest is just too much gibberish to try and decipher. You seem to be having some electrical issues, but it's going to take better work that thus far to determine and permanently resolve them.
I had taken the car back once a few weeks ago when the start-stop and engine light error first popped up, they cleared the errors and said the car was driving fine so let me take it away, it was driving fine until now. They said it may not come back after a clear of the system or it could be the "ABS return flow pump" which is shown in that list. I am new to Audi so im not too sure about the car as of yet. I will take it back to the dealer again and see what they say.
Well, enjoy those little moments when you can. :-)
But the fuses in question are not in the normal fuse panels, they are in the connector station at the base of the A-pillar, such as here: https://forums.ross-tech.com/index.p...01/post-120532
The G1, G2, and F are the three ABS fuses for a right-hand drive B8.0 A4.
What your picture makes clear though is that you have a B8.5 model, not a B8.0 model. In the US MY12 is all B8.0. But they started making B8.5 for RoW in 2012. Your fuses were not making any sense as a B8.0, but match exactly once I looked at the B8.5 diagram. Not that it makes any different to the ABS fuses, but you should always point out when starting a thread that you have a B8.5 2012 A4, not just a 2012 A4.
But that it seems to be glitching between working and not working, and the not working seems to be around electrical issues, I'd be wondering about corrosion of the wiring and parts. Maybe you have water issues behind that kick panel. The kick panel is easy to remove on the passenger side since there's no hood release latch to mess with. Remove the fuse panel cover, remove the gap cover between the A-pillar and the kick panel (sill panel), and then start working the sill panel up starting from the front, then pull it rearward and out.
01-26-2021, 12:40 AM
Auto Start Stop malfunction Help
