Repeated 12V Electrical Issues on CUPRA Leon 2024 – Anyone

[Kikd]

Hey everyone,

I wanted to share my experience with my CUPRA Leon 1.5 eTSI 150 CV DSG (2024 hybrid) and see if anyone else has faced something similar.

My car has suffered from repeated 12V electrical issues — basically, the vehicle refuses to start.

It’s currently on its fourth repair visit, and while it was temporarily fixed, the problem has started appearing again.

Here’s a quick timeline of what’s happened:

1st time (Oct 2024): The car was simply restarted and returned to me.

• 2nd time (Apr 2025): The 12V battery was replaced.
• 3rd time (May–Aug 2025): The alternator was replaced after weeks of waiting for parts.
• 4th time (Oct 2025 – ongoing): The 12V battery was replaced again, but the problem has returned. For example, one evening when I went to drive the car, the 12V battery warning light was on, and as soon as I started the engine, the light went off.

Each time the problem temporarily disappears but returns after a few months.

I’ve also had to travel several times between Pisa and Prato for these repairs, which has been both time-consuming and expensive.

Has anyone else experienced 12V or electrical system failures on their Leon eTSI hybrid?
If so, what was the root cause, and did CUPRA eventually find a permanent solution?
I’m now considering taking formal action / pursuing a claim to resolve this — has anyone successfully done this before?

Any insight or shared experience would be really helpful — thank you!

 

[trucker0werner]

Do you use charge schedule. Saw message that this can cause it will drain te battery.
Or update to the latest software version.

In that state the car is being kept online to wait and start the charging schedule.

If you do the same as me and directly charge the car and after that disconnext it. Then it should be something else.

Battery only drains as long you have something on.


On hybrid is it not that you jave an dcdc converter. Device that converts dc voltage to 14v to charge battery

 

[Kikd]

Do you use charge schedule. Saw message that this can cause it will drain te battery.
Or update to the latest software version.

In that state the car is being kept online to wait and start the charging schedule.

If you do the same as me and directly charge the car and after that disconnext it. Then it should be something else.

Battery only drains as long you have something on.


On hybrid is it not that you jave an dcdc converter. Device that converts dc voltage to 14v to charge battery

is eTsi hybrid

 

[James_R]

is eTsi hybrid

The 150 eTSI is a mild hybrid with a 48v system and no external charging capability.

 

[Kikd]

The 150 eTSI is a mild hybrid with a 48v system and no external charging capability.

Just had the 5th failure.
Drove from Pisa to Prato, after parking for 10 minutes, the dashboard lit up but the engine wouldn't start (have video). After waiting 5 minutes, it fixed itself.

Hybrid version, never charged. The workshop has done 3 repairs (replaced battery twice, generator once), but the problem continues to happen.

 

[James_R]

Have they checked for software updates?

 

[Kikd]

Have they checked for software updates?

every time

 

[James_R]

And they have applied the PV2.2 updates?

 

[Kikd]

And they have applied the PV2.2 updates?

like this？

 

[James_R]

Send me your VIN in a private message and all check the software versions for you

 

[trucker0werner]

Ah its a mild hybride.
Got confused, because I have an 1.5tsi Ehybrid.
Needed to check it up. but thanks to the word Etsi and hybrid as name I made the misstake.

Now I as well understand that it could have an alternator. Because I believe I do not have it. That the generator is being suppling HV DC voltage to the HV battery and the DCDC converter is charging the 12v battery.

But even does cars had 12v issue regarding the Multimedia system.

Myself I have 2650 as version. If I am correct this is an MIB4 version radio MIB3 version latest is 1988.
But stil unknown how I get the latest version. Seems to be going OTA. Map version seems to be changed over time.

@James_R
Seems that you are more aware on how to check the correct version and you have more info regarding PV2.2 or PV4 version.
Is this indeed going OTA or is that we need to install it our self

 

[James_R]

2650 is the latest version of software available at this point in time.

The PV updates won't be OTA, they're far too complex, they will need to be installed by your local dealership.

 

[LJamH]

I can't say much for Seat however this is fishy to me, I'm a ford tech. But I prefer Seat as a car to own.
Most MHEVs actually use the 48V system for starting the car.
The 12V System is purely for auxiliary electricals. However it can be used to start the car in the event the 48V is at a low SOC.
MHEV's also don't have a starter motor or alternator.
They have a starter generator, a device which does the job of both.
We had this exact issue on on a MHEV Focus, Non start, suspected 12V issue.
It was the module inside the 48V battery. It was a fun one to diag.
We replaced the 48V battery and the fault was resolved.
Basically the car believed the 48V battery was charged and was attempting to use it to start the car but the 48V was flat.
It wouldn't revert to the 12V so yea, not starting.

I'm unsure if the module and the battery are one unit on your vehicle or separate. They are likely one unit.

I suspect the 48V battery on your vehicle or the module which controls it are faulty on your vehicle.
The 12V is often charged via the 48V battery if that isn't happening that explains the fault.

Now this diagnostics is assuming Seat use a similar system to ford.
I may be incorrect however I would prompt you to ensure the 48V system is functioning as intended instead of simply firing parts at the car.

 

[Kikd]

I can't say much for Seat however this is fishy to me, I'm a ford tech. But I prefer Seat as a car to own.
Most MHEVs actually use the 48V system for starting the car.
The 12V System is purely for auxiliary electricals. However it can be used to start the car in the event the 48V is at a low SOC.
MHEV's also don't have a starter motor or alternator.
They have a starter generator, a device which does the job of both.
We had this exact issue on on a MHEV Focus, Non start, suspected 12V issue.
It was the module inside the 48V battery. It was a fun one to diag.
We replaced the 48V battery and the fault was resolved.
Basically the car believed the 48V battery was charged and was attempting to use it to start the car but the 48V was flat.
It wouldn't revert to the 12V so yea, not starting.

I'm unsure if the module and the battery are one unit on your vehicle or separate. They are likely one unit.

I suspect the 48V battery on your vehicle or the module which controls it are faulty on your vehicle.
The 12V is often charged via the 48V battery if that isn't happening that explains the fault.

Now this diagnostics is assuming Seat use a similar system to ford.
I may be incorrect however I would prompt you to ensure the 48V system is functioning as intended instead of simply firing parts at the car.

Thanks — I really appreciate the technical tips and everyone’s input.


At this point it’s not the main issue anymore: I’ve decided to stop testing fixes myself and to pursue formal legal action. I have multiple repair orders, dated videos/photos of the faults, and correspondence (PEC) with the dealer/brand, and I’ve started working with a lawyer. I’m going forward with a consumer complaint and will consider court action (summary procedure) if needed.





If anyone here has gone through a similar litigation or has experience dealing with warranties/consumer law in Italy for repeat MHEV/12V-48V issues, I’d be grateful for any pointers or references. Thanks again.

 

[James_R]

Will more than likely be resolved when the new PV update suite is released and applied.

Upto model year 2025 most vehicles were still being fitted with a starter motor as well as a starter generator. The starter motor is no longer fitted as of model year 2026.