Audi A7 total fail

[Paul JA]

Hello everyone,

I'm starting a fresh thread here because I have dabbled in a few existing threads which are not 100% relevant to my issue(s).

I have a 2012 A7 3.0TDI 242bhp

So where do I start, well here;

1 ACC and start/stop error message flagged up some mornings, I could stop and restart the car no problem and message would go away. Assumed battery on the way out, so got a new battery.

2. more serious error messages started flagging up and battery voltage would drop over night, so fitted new battery. This didn't work and even new battery was still draining. When the engine was running (before total failure) voltage was a decent 14.5v or so with engine running so thinking was alternator ok.

3.Assumed power losses were due to not coding new battery and the energy management system was draining it, so bought VCDS to code battery in. Did this but this still didn't solve problems.

4. Even attaching jump leads car wont start at all now, gearbox malfunction message prevalent, took new battery out again to recharge, thinking low voltage could still be an issue, reinstalled with healthy voltage but all error messages still showing, now even more error message showing up tmps, garbox malfunction, stability program, etc etc.

5. VCDS will not communicate with car now, VIN not recognised by software.

6. Charged up old battery as a matter of interest and found out it has been holding 12.73v for 5 days now so it was never at fault.. So what is the problem??

7. Assuming now not a battery fault, (now that I cant get car started battery doesn't seem to go flat) I looked again at various forums and issues. Looked at central gateway module under back seat sprayed contact cleaner on circuit board in the hope that that might be the issue, have no way of checking if a fault here as VCDS doesn't work, but still same errors everywhere and car doesnt start, so not the issue (does anyone know if the gateway module which appears to have two plugs on it unplugs? one plug is easy the other I couldn't unplug and I really didn't want to break anything (more)). Now thinking it could be the gearbox sensor that I've heard about. so this is where I'm at..

Has anyone else had this sequence of issues? if so how was it fixed?

Thanks everyone..

Paul.

[Magnet]

Before moving on Paul, could you tell us whether the starter motor turns the engine over enthusiastically enough, but it wont start, or if the starter motor doesn’t turn the engine over at all? 
Kind regards,

Gareth. 

[jdragon]

If the starter is turning well, I'd try manually resetting the ECU 🙂

[Paul JA]

11 hours ago, jdragon said:

If the starter is turning well, I'd try manually resetting the ECU 🙂

Hi thanks for these suggestions. Gareth, once or twice I've thought the car was going to start did start turning over but then the gearbox malfunction message cuts in and stops it, its as if something blocks the command to start the engine, its keyless so it's difficult to repeatedly turn the car over like with a normal key in ignition. I would say the starter is good its just prevented from working. 

Jdragon, that sounds like a good idea, it cant do any harm to reset, how would i go about doing this? 

Many thanks,

Paul. 

[jdragon]

Google "how to reset audi ecu"

There are several ways, I wouldn't like to suggest one over the other 🙂

[Paul JA]

3 hours ago, jdragon said:

Google "how to reset audi ecu"

There are several ways, I wouldn't like to suggest one over the other 🙂

Thanks, I've tried all the methods on google  I can see, none work unfortunately, or at least not for me.

[jdragon]

It was worth a try 🙂

The reason I suggested is that when my friends A3 (2011 model) was ready to be replaced pretty much every light came on in the car as a result, even after replacing the battery. The local garage did a manual reset and everything was OK after.

Seems very strange VCDS won't communicate with the car. I'd start a thread about that and post a scan (if you have one) on the Ross-tech forums to see what feedback you can get.

Have you checked the alternator? Perhaps taking the car to an auto electrician is the next step?

[Paul JA]

thanks for your help, it is appreciated, Yeah I'm just trying to bottom out as much as I can before getting a specialist in (not that I know of one locally yet).

I don't know why the vcds isn't working, that's another issue in itself. I still need to keep an open mind that it could be something alternator related or something to do with the battery charging, but the car has been fine when it was running, I think VCDS was also ok when the car engine was running. There is an answer out there somewhere, I'm still keeping an open mind about the battery not being right. I know voltage is fine, but there are other elements to a modern battery which I don't know how to check, is it possible the battery has decent voltage, but still lacks the power to start the engine? how would I check this?. It is my second "new" battery though and the old battery is holding charge but maybe it is failing in some other way also. Does this make sense to anyone?

[jdragon]

You'd need to check the battery Amps