Faulty transmission

Black Pearl

Registered User
Hi all,

So I have the dreaded 2010 S4 DSG. I have been reading for the past couple of days now and I cannot find my symptoms with any other issues. When cold my transmission works fine but as soon as it starts to warm up there is roughly a 6 second delay in first to 2nd gear. All other gears are fine. I haven' had any warnings and there are no error codes. I have just hit the 75k Mark and I am due a transmission fluid change which I will be doing. The issue happend first at 75001 which I find strange.

Now there is no history on having the mechatronic unit replaced that I can see but when I take the pan off to replace the filter will I be able to see if it has been done? Also should I replace anything else while I am in there?

Thanks in advance
 

Mario

Registered User
Service the gearbox first and take it from there and hopefully you are lucky and that fixes

+1 give it a proper service with genuine Audi fluid and filters, then go from there. These days there are even companies which can repair faulty mechatronic units and swap out individual actuators if needed.

Fists things, first though. Give it a good service.
 

Black Pearl

Registered User
20180201_094252.jpg


Here it is, the ugly mechatronics. I decided to pull it out as I have all the seals and what not. I checked it all over, tested the solinoids and nothing everything looks brand new. Even the fluid was nice and clear. There was a couple of metal flakes very small I hope this isn' the issue. I'l be putting everything back tomorrow when the gasket arrives. Also brought some new spark plugs and I have a done an oil change.

If this doesn't resolve my issue I have no idea on what it could be apart from possibly a software update or something.
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
I like the selection of tools. Knocking stick number 1 , looks like it's not had too much use. Those things are so complex with tiny oil passages that can get blocked and a lot more gubbins hidden away. There are almost always metal flakes floating around in a gearbox just a matter of how many .
Is it the original part, what is the part number ?.
 

Black Pearl

Registered User
Haha funny enough I have only had to use it once and that was for an oil change, couldn' get the filter housing off.

That' good then there was 2 or 3 flakes maybe 2mm big. Oh no, I have scanned all over the unit trying to look for little nooks. Also there is so many part numbers for each bit, everything has the the Audi logo of what I can see.
 

Mario

Registered User
How did you test each solenoid? Did you strip it all down and apply a 12v (I think, need to double check) source directly to it and hear it clicking on & off?
 

Black Pearl

Registered User
Yeah I stripped it down and tested it. Ill check that out too. Tempted to just trade it in and get a newer s4.
 

Mario

Registered User
Older Mechatronic units are also known for issues with the PCB which can cause the symptoms you are seeing. This is due to lack of protection from the hot oil which over time causes damage, especially as the oil gets older / dirty and more acidic.

Newer units don't have this issue due to better protection. You can buy a replacement PCB and swap it out, they cost about $370 for the kit from ECS Tuning in the states. They do show the Audi part no. on their website though, so be worth checking with @creweaudiparts how much it costs for part 0B5398009E

Link to the ECS website.... https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/mechatronics-repair-kit/0b5398009e/

Also, if you want I can look in ElsaWin for the the full guide on replacing the PCB, inc all torque specs, etc when re-fitting.
 

Black Pearl

Registered User
Thank you both for the reply, I have placed an order through ecs a couple of days ago just waiting for it to turn up. I have the pcb off at the moment and they look fine I don't see exactly how this unit could be damaged. The unit is completely sealed apart from the ends. I'l swap them out and go from there.
 

Mario

Registered User
I have the pcb off at the moment and they look fine I don't see exactly how this unit could be damaged.

Constant heating and cooling to components that are not adequately protected will cause the solder joints to fatigue and crack. These can be mico-fracture and as such when cold they give a good connection, but when warmed up and they expand the connection breaks and causes faults like you see.

This is a bit like the XBOX 360 3RL of death that used to occur. The permanent fix for those was to remove the BGA and reball with leaded solder as leaded solder is more malleable and less prone to cracking than lead-free solder.

However due to RoHS laws which are implemented all manufacturers must use lead-free solder in all electrical / electronic components these days, but the lead-free solder comes with it's own issues in terms of reliability.
 

Dippy

Registered User
And its not just the PCB - impurities or flaws in the internal packaging of microchips can be affected by the heat cycle and lead to a failure. That's not something you can see from inspection.
 

rum4mo

Registered User
Oh, I'm glad that still have adequate stock of old style solder, that claw hammer, that people that like wood use, you could have said that you were only using the hard plastic handle to tap things free - that might have worked?

Edit:- being required to start using lead free solder did annoy avionics manufacturers a bit!
 

razza1

Registered User
You can find out from scanning it when in the car if it’s a new or old mech unit. It will list the part number as part of the full scan with something like carista. 8k1 is the new one 8k0 is the old one prone to failure (from memory)


Sent from my iPhone using Tapatalk
 

Black Pearl

Registered User
thank you all for the replies, i really hope the new pcb will solve the issues if not i have come across TSB 2011732 which is a software update. As for the part numbers razza1 mine all start with 0B5 for the unit.
 

scotty76

Registered User
You can find out from scanning it when in the car if it’s a new or old mech unit. It will list the part number as part of the full scan with something like carista. 8k1 is the new one 8k0 is the old one prone to failure (from memory)


Sent from my iPhone using Tapatalk
I seem to have...

Transmission
Part #: 8K5927156B
 

Black Pearl

Registered User
So I decided to change my spark plugs today and they were nasty!! I took a picture.
20180202_150223.jpg


Would this cause a lag in acceleraion?
 
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