Help Please Audi S4 gearbox overheating?

[AudiS4B8Auto]

2 days ago I got a warning sign “gearbox malfunction you may continue driving” with check engine light.
My car won’t move anymore, got towed home, after 2 days when I start the car, everything was fine, no warning nothing, check engine light also disappeared.
I changed my mechatronic unit around a year ago, sadly it’s out of warranty.
I don’t know what to do now, I don’t want to spend another $5k to change the mechatronic unit, anyone knows what’s going on with the car? Thanks

 

[Cerbera9]

My car has also experienced issues in the hot weather and lack of cool air flow, bouncing idle, slow gear changes and "kangerooing" throttle although when cool the car performs and shifts perfectly.
The OE gearbox oil cooler is built in to the drivers side of the coolant radiator and I have for a while suspected this is the cause of the issue especially if you have an uprated heat exchanger like I do which is mounted in front of the coolant rad blocking some of the airflow. I think the solution it to add and additional transmission cooler mounted behind one of the fog light covers same principle as those added to heavy automatic tow vehicles.

 

[AudiS4B8Auto]

My car has also experienced issues in the hot weather and lack of cool air flow, bouncing idle, slow gear changes and "kangerooing" throttle although when cool the car performs and shifts perfectly.
The OE gearbox oil cooler is built in to the drivers side of the coolant radiator and I have for a while suspected this is the cause of the issue especially if you have an uprated heat exchanger like I do which is mounted in front of the coolant rad blocking some of the airflow. I think the solution it to add and additional transmission cooler mounted behind one of the fog light covers same principle as those added to heavy automatic tow vehicles.

So after that overheating issue never happened again? Where I can buy the transmission cooler? Thanks for the help

 

[Cerbera9]

My car never actually overheated or got to the stage of warning lights/messages or the car not working I just noticed a big difference as described.
I've looked for a transmission cooler kit specific for our platform but there doesn't seem to be one available so it will be a case of purchasing a suitable universal transmission cooler, size dependent on fitment location and connecting to the OE oil lines. I'm just looking in to this myself but a few people in the US on Audizine forum have carried this out.
Ebay or any motorsport spares places such as Demon Tweeks or Merlin motorsport etc will supply transmission coolers.

 

[Mario]

First question, what is the year of manufacture for your car?

Next, you probably never needed to replace the full mechatronic unit last year to begin with, just the PCB is what tends to be required. Pre-2013 cars have less protection / cooling and the constant heating / cooling as well as acidity from old oil will damage the electronic connections on the PCB and cause all sorts of issues.

New PCB's is only £300 or $400 from ECS if you are in the US.... https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/mechatronics-repair-kit/0b5398009e/

Read the following thread IN FULL. I have provided a full list of part numbers required, quantities, etc, etc for the PCB swap including a download link to the pages from the workshop manual on how to perform the PCB replacement.

The OP in this thread said it took them 4 hours start to finish, but it fixed their faults. If your car is pre-2013 then I would do the PCB replacement AND sort out better cooling for the gearbox. If it's post-2013 then the factory cooling should be adequate, but ultimately a new PCB will be required to resolve your faults and a full fluid change at the same time.

https://www.audi-sport.net/xf/threads/new-b8-s4-owner-with-problems-s-tronic.366115/

 

[AudiS4B8Auto]

My car never actually overheated or got to the stage of warning lights/messages or the car not working I just noticed a big difference as described.
I've looked for a transmission cooler kit specific for our platform but there doesn't seem to be one available so it will be a case of purchasing a suitable universal transmission cooler, size dependent on fitment location and connecting to the OE oil lines. I'm just looking in to this myself but a few people in the US on Audizine forum have carried this out.
Ebay or any motorsport spares places such as Demon Tweeks or Merlin motorsport etc will supply transmission coolers.

First question, what is the year of manufacture for your car?

Next, you probably never needed to replace the full mechatronic unit last year to begin with, just the PCB is what tends to be required. Pre-2013 cars have less protection / cooling and the constant heating / cooling as well as acidity from old oil will damage the electronic connections on the PCB and cause all sorts of issues.

New PCB's is only £300 or $400 from ECS if you are in the US.... https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/mechatronics-repair-kit/0b5398009e/

Read the following thread IN FULL. I have provided a full list of part numbers required, quantities, etc, etc for the PCB swap including a download link to the pages from the workshop manual on how to perform the PCB replacement.

The OP in this thread said it took them 4 hours start to finish, but it fixed their faults. If your car is pre-2013 then I would do the PCB replacement AND sort out better cooling for the gearbox. If it's post-2013 then the factory cooling should be adequate, but ultimately a new PCB will be required to resolve your faults and a full fluid change at the same time.

https://www.audi-sport.net/xf/threads/new-b8-s4-owner-with-problems-s-tronic.366115/

Im driving 2011 Audi S4
Thank you for the reply. Sadly I live in Canada, the part cost me $700 to get here
But it’s better than $5000 for the mechatronic

 

[Mario]

$700 Canadian is about £400 or $530 US. Is it not cheaper to buy the one from ECS for $400 US and have them send it across to you?

2011 car would explain the issues, as I mentioned above, pre-2013 cars had inadequate cooling / thermal protection for the PCB. If you replace the PCB and improve the gearbox cooling it should hopefully sort your issues out once and for all.

Let us know if you need any more help, but full details and instructions should be in the thread I linked to in my last post.

 

[AudiS4B8Auto]

$700 Canadian is about £400 or $530 US. Is it not cheaper to buy the one from ECS for $400 US and have them send it across to you?

2011 car would explain the issues, as I mentioned above, pre-2013 cars had inadequate cooling / thermal protection for the PCB. If you replace the PCB and improve the gearbox cooling it should hopefully sort your issues out once and for all.

Let us know if you need any more help, but full details and instructions should be in the thread I linked to in my last post.

$700 Canadian is about £400 or $530 US. Is it not cheaper to buy the one from ECS for $400 US and have them send it across to you?

2011 car would explain the issues, as I mentioned above, pre-2013 cars had inadequate cooling / thermal protection for the PCB. If you replace the PCB and improve the gearbox cooling it should hopefully sort your issues out once and for all.

Let us know if you need any more help, but full details and instructions should be in the thread I linked to in my last post.

$700 Canadian is about £400 or $530 US. Is it not cheaper to buy the one from ECS for $400 US and have them send it across to you?

2011 car would explain the issues, as I mentioned above, pre-2013 cars had inadequate cooling / thermal protection for the PCB. If you replace the PCB and improve the gearbox cooling it should hopefully sort your issues out once and for all.

Let us know if you need any more help, but full details and instructions should be in the thread I linked to in my last post.

From US sourced the part it would be the same after the conversion of the exchange tax and shipping, right now I'm arguing with Audi Canada, because I repaired at Audi less than 2 years, they say if it's the same problem they will cover from 10-70%, and I also got a quote from a private shop that they can change the PCB for $1500-2500 maybe a little over, do you think it's a fair price? Sadly I don't have the ability to change it by myself, so I'm just wondering if that's the right price for it or no? I don't want to spend that much money anymore, not trying to cheap out, do understand me

Thank you again for the help!

 

[AudiS4B8Auto]

Just got back from Audi
And they said I need to replace the transmission sensor, code: g676
$2k for the part
$5k for labour
My car not even worth that much