Car battery rating on 2.0 TDI KL

Apr 8, 2025
10
1
Bought my KL ST 2021 2.0 TDI two days ago. Yesterday while driving it's starts to go off with all kinds of system failures (Drive system, Travel assist, Side assist), and on top of that, the oil temp. meter is going nuts, starts fluctuating and rising violently between 70 C and 130 C.
Talked to a few mechanics and my dealer (official VAG representative in my country) today, and one of them says it might be a battery problem.
I decided to chase that idea and go to a shop nearby where they have a more proper battery diagnostic tool and it spits out this:

1744207907425.jpeg


He said the battery is shot, probably the reason for all the failures.
Anyone have experience with this?

I'm calling my dealer tomorrow to get it replaced. It's covered by our consumer protective law which ensures me from things like this.
But still, I'm not 100% sure, if this is the root cause.. I might be a bit anxious when it comes to expensive things breaking down 😅 Then again, who isn't..
 

Seriously?

Active Member
Apr 20, 2018
1,443
1,041
Battery "resting" voltage should be around 12.6V
Getting close to the 12V mark suggests it's almost fully discharged.
Modern car electronics hate under-volts and can display the symptoms your car is showing.
 
Apr 8, 2025
10
1
Yeap, I thought so also. I just sat in right now for a few minutes trying to set a few things up and the 12V battery warning showed up.
I'll get it replaced asap and post here after, to confirm if this resolved all my issues
 

Yern

Active Member
Apr 25, 2019
691
350
I had none of the other issues 12 months ago on my previous 22 plate MK4 except for the fluctuating oil temp, exactly the same behaviour. The dealer replaced the oil temp sensor and this cured the problem. Perfect since until I just changed the car.
 
Apr 8, 2025
10
1
Yesterday, I was at the SEAT dealer so that they could replace the battery. They changed it, and we went on a test drive. The errors were still there, and the oil was still swinging. All in all, the mission failed successfully. My head was spinning on the way home, not a really good experience with a car I was anticipating the most out of all I had.
This morning I took it to the washing station and then took it for a short drive ca. 30min. No errors, no failures and most of all, the oil temp. wasn't swinging...
It was rising slowly as it normally should, and stayed stable.
I'm dumbfounded, no idea what is happening.
I'm thinking software issues, since from what I've read I seem to have an old version (1804) and I've tracked much more current versions for it. Just don't know how to update. I'll have to search for this.
 

cairus

Active Member
Jun 4, 2024
1,435
519
I know that the combined oil sensor is prone to failure. It was replaced and everything was fine again.
 
Apr 8, 2025
10
1
Quick update, had a visit to the dealership. They diagnosed the problem, and it seems to be a faulty drive selector switch?? No idea how it's connected to the swinging oil temp gauge.. The lady just said there's a fault in the switch, she didn't know more since she's just a mediator between me and the mechanic and I can't freaking talk to the mechanic directly...
All the problems disappeared for about a week, then reappeared a few days back again, so my car's going berserk as soon as the engine oil gets warm enough.
Thankfully the switch will be replaced under warranty, but I have to wait for 3 goddamn weeks for the date they've set me.
Not really convinced all the problems are connected to the switch, but I guess I'll have to wait... I really need to buy an OBD if this is going to be a thing from now on
 
Apr 8, 2025
10
1
Just an update in case somebody will have similar issues and is looking for answers: I got the drive selector switch replaced with a new one and so far, it's been a few weeks now, no problems at all.
So it seems that the root of all errors and warning and assists has in fact been a faulty drive selector switch in the center console used to select a gear for DSG transmission.
Cheers!
 

KoNG

Active Member
Jul 27, 2016
535
118
London
Just an update in case somebody will have similar issues and is looking for answers: I got the drive selector switch replaced with a new one and so far, it's been a few weeks now, no problems at all.
So it seems that the root of all errors and warning and assists has in fact been a faulty drive selector switch in the center console used to select a gear for DSG transmission.
Cheers!
I heard that this is a known issue, especially in early build cars
 
Apr 8, 2025
10
1
If it is, it might explain why I wasn't required to open a wallet for this replacement 😛
Have to take a look for other possible known issues on this model so I don't get another surprise in the future
 

KoNG

Active Member
Jul 27, 2016
535
118
London
Your main issue will be a software problems. There was a recall that required update several electrical modules. Look for the thread here. Plus infotainment unit, reversing camera lens and you should enjoy the ride afterwards 😁
 
Apr 8, 2025
10
1
Oh boy.. Hopefully the first owner had most of these things resolved already. So far it's been more or less fine, with occasional assist "unavailable" for a few minutes and then coming back online, everything else seems to work.. Fingers crossed!
I even updated my infotainment unit to 1896 version just 2 days ago.
But will post if anything else happens in the future 🙃
 
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