After coming from shopping, the key remote opened the door normally, but when I sat down I realized that the car has lost power completely.

There's no sign of electricity nor the remote is responding.

What could have happened? Maybe a fuse blown? I'm stuck in a car park at the moment so any ideas would be welcome.

Octavia 4 1.4 TSI PHEV SW

@Ootohere will probably know who best to ask.

I believe your issue is with the 12V battery - even if the main battery is charged, without the 12V you're going nowhere.

6 minutes ago, OccyVRS said:

@Ootohere will probably know who best to ask.

I believe your issue is with the 12V battery - even if the main battery is charged, without the 12V you're going nowhere.

I doubt it very much, because I drove it only 10 minutes ago and everything was fine. Plus I do check my battery regularly as I go on long distance trips.

15 minutes ago, Octawia said:

remote opened the door normally

If it opened normally, does the car still close/lock from remote? That would be a sign that 12V is still alive.
With the steering on the proper side of the car ( I see you're in Finland) I suppose you can open the engine bay. Try to connect an external 12V there; there's a "+" connection point in the fuse box (no need to go directly to the 12V battery.

9 minutes ago, SkOmk4 said:

If it opened normally, does the car still close/lock from remote? That would be a sign that 12V is still alive.
With the steering on the proper side of the car ( I see you're in Finland) I suppose you can open the engine bay. Try to connect an external 12V there; there's a "+" connection point in the fuse box (no need to go directly to the 12V battery.

Yes, it did open with the remote, but now there's zero sign of life. It doesn't lock with remote. There are no sign of life at all.

I just charged the EV battery 30 minutes ago and drove the car for 100m and made a stop at a shop. When I came back, it's in this state. I've been using it EV mode usually. I don't even bother with the petrol engine these days.

I am certain that the battery is working properly. There must be some other reason for total loss of power in 10 minutes sleep.

Edited 6 August, 20256 Aug by Octawia

If the 12V battery has a short circuit, it will be empty in a short time... How do you test the battery? With a load test? Everything else is worthless.

1 minute ago, Cairus said:

If the 12V battery has a short circuit, it will be empty in a short time... How do you test the battery? With a load test? Everything else is worthless.

Even with a battery short circuit, it would display some kind of error message on the dashboard. This is like completely dead. I'm going to try locking the doors and calling a tow service tomorrow (hopefully I can put the automatic gear into N mode somehow manually).

Could be the key, especially if cannot lock car again.

The key battery level might be enough to illuminate a red LED but not enough to transmit that correct key is in vehicle.

Try replacing key battery with best battery you can buy (not one of those weak pound shop type batteries).

If coming back tomorrow try second key, and if safe place, consider unlatching the bonnet as it will be pig to open if can't get into car to release it.

Edited 6 August, 20256 Aug by SurreyJohn

+1 for opening the bonnet now, although that said you should still be able to get in manually.

AFAIK even if the key is completely dead, the car should show some sign of life.

I was meaning 12V battery not as necessarily the battery itself, but that system. That is the only failure that would cause the car to die entirely, with nothing working.

To stick it into neutral manually you'll need to lift up the DSG shifter facia and find the little yellow level. Then you have to release the EPB - I've no idea how to do that.

It could well be the key, but if it was dead then I doubt it would unlock itself and then die a second later. It also doesn't explain the dead car.

5 minutes ago, OccyVRS said:

+1 for opening the bonnet now, although that said you should still be able to get in manually.

AFAIK even if the key is completely dead, the car should show some sign of life.

I was meaning 12V battery not as necessarily the battery itself, but that system. That is the only failure that would cause the car to die entirely, with nothing working.

To stick it into neutral manually you'll need to lift up the DSG shifter facia and find the little yellow level. Then you have to release the EPB - I've no idea how to do that.

It could well be the key, but if it was dead then I doubt it would unlock itself and then die a second later. It also doesn't explain the dead car.

I very much agree. If the battery would be dead completely, it would still have some kind of life. I'm wondering if there's a fuse somewhere that may be controlling it all. I checked the fuse diagram but I could not find any fuse that would shut it all down at once.

I mean, I agree with others about the battery dying, but sudden no sign of life, clearly points to something else.

I charged the EV battery only couple of hours ago, so that cannot be the culprit. Thinking back, after charging, I disconnected the charging cable, started the EV mode normally. When reversing I did hear a weird clack sound coming somewhere, I didn't think it was from my car. Then I put it in to Drive mode and drove about 500m then stopped and parked normally. Then when I came back unlocked it with the remote, but when I sat down I saw no sign of life in the cockpit. Even the key didn't lock or unlock after that.

@SurreyJohn it cannot be the key battery as I replaced it about a month ago. Hence the key lights up when I press the buttons.

Edited 6 August, 20256 Aug by Octawia

There is a pyrofuse, but that's not to do with the 12V battery.

I suspect whatever the issue is, is under the bonnet. AFAIK there is no fuse that will cut off power to the entire car from the 12V battery. I may be wrong.

If the car is dead due to the battery, then it is completely dead. I've never really seen a battery die fully - there is always enough to at least make the alarm light flash or something.

13 minutes ago, OccyVRS said:

completely dead. I've never really seen a battery die fully - there is always enough to at least make the alarm light flash or something.

Every vehicle with a defective battery didn't even display the immobilizer LED... if the battery is defective while stationary, the vehicle won't give any notification at all... the HV interlock release is located in the engine compartment. The pyrotechnic explosion affects the HV battery.

3 minutes ago, Cairus said:

Every vehicle with a defective battery didn't even display the immobilizer LED... if the battery is defective while stationary, the vehicle won't give any notification at all... the HV interlock release is located in the engine compartment. The pyrotechnic explosion affects the HV battery.

Regardless, the HV system could be at a full SoC and still have no impact on anything if the 12V battery/system is dead.

I would suggest the issue lies within the 12V system - regardless of the HV system, KESSY system or whatever else, there should be some signs of life in the vehicle.

@Octawia my suggestion would be to establish if the 12V battery is dead or not. If it is, you have the problem (for now - you’ll have to figure out why it died). If it’s charged, the issue is elsewhere.

I’m unsure of the procedure regarding topping up/using a battery booster on a PHEV, but others will be able to advise. I also see no reason why a manual unlock and bonnet release isn’t possible if the battery is entirely dead.

The only question I do have, for you right now - does locking/unlocking the car manually definitely work? I believe it should be, but I would still check.

I’d also get in touch with Skoda and a proper recovery company (first thing in the morning now) as you might have issues getting that EPB to release if the car is entirely dead.

Any vehicle HV battery is useless with a dead 12V battery because the vehicle's electronics won't boot up.

Is the vehicle affected by the field measure where I think the gateway was the one that deeply discharged the 12V battery because it did not go to sleep

14 minutes ago, OccyVRS said:

Regardless, the HV system could be at a full SoC and still have no impact on anything if the 12V battery/system is dead.

I would suggest the issue lies within the 12V system - regardless of the HV system, KESSY system or whatever else, there should be some signs of life in the vehicle.

@Octawia my suggestion would be to establish if the 12V battery is dead or not. If it is, you have the problem (for now - you’ll have to figure out why it died). If it’s charged, the issue is elsewhere.

I’m unsure of the procedure regarding topping up/using a battery booster on a PHEV, but others will be able to advise. I also see no reason why a manual unlock and bonnet release isn’t possible if the battery is entirely dead.

The only question I do have, for you right now - does locking/unlocking the car manually definitely work? I believe it should be, but I would still check.

I’d also get in touch with Skoda and a proper recovery company (first thing in the morning now) as you might have issues getting that EPB to release if the car is entirely dead.

Yes I think you are right. It must be either the 12v battery or the battery system in general that cut out the power entirely. The fuses are so small that I have no way of checking which one is working or which one is blown. I'll bring a multimeter with me tomorrow.

As the doors are unlocked, there's no problem getting into under the bonnet as the latch is operated by manual wire.

The setbacks are that I'm in a multi-story car park so the towing car won't be able to tow it out of the car park, also even if I somehow manually managed to put it into neutral gear by the safety lever, the parking brakes are on I'm not sure if there's a method to unlock those.

I also tried to remove the plastic cap that covers the keyhole, in hope to lock the doors for safety overnight, but I wasn't successful. I will contact the Skoda's service in the morning as it's covered in my service package.

In a way I feel fortunate because recently I completed a 7,000 km trip across weird parts of Europe and this could have happened anywhere inconvenient (though I do wish it happened when I was in Czech Republic 😂).

I will update this topic once I get some results as it can happen to anyone.

Forget your HV battery circuit when the vehicle isn't running. As long as the vehicle isn't running, the 12V battery does everything on its own.

3 minutes ago, Cairus said:

Forget your HV battery circuit when the vehicle isn't running. As long as the vehicle isn't running, the 12V battery does everything on its own.

Yes - the 48V system is irrelevant. Either your battery is dead (most likely scenario) or you've got a failure elsewhere.

It's very unfortunate it's happened in a car park, but hey, I suppose there could be worse places - at least access is fairly limited and it's not like anyone will be going anywhere in it!

If there's no power and it's fully unlocked the you can't lock it anyway - the key only works for the drivers door.

My personal choice would be to get a battery booster, get back there in a few hours, and at least try to lock the car. I'm not sure I'd leave it unlocked in a car park overnight, even in Finland.

5 minutes ago, OccyVRS said:

Yes - the 48V system is irrelevant. Either your battery is dead (most likely scenario) or you've got a failure elsewhere.

It's very unfortunate it's happened in a car park, but hey, I suppose there could be worse places - at least access is fairly limited and it's not like anyone will be going anywhere in it!

If there's no power and it's fully unlocked the you can't lock it anyway - the key only works for the drivers door.

My personal choice would be to get a battery booster, get back there in a few hours, and at least try to lock the car. I'm not sure I'd leave it unlocked in a car park overnight, even in Finland.

Even if I got a battery booster, I'm not sure where to connect it as the 12V battery is well concealed under the rear seats in the PHEV Combi (station wagon).

Then read your vehicle's manual. There is a connection for this in the engine compartment.

What he said ^

Most PHEVs will have some sort of connection either in the boot, or the engine bay.

Is the second post in this thread true @Cairus? I'd phone Skoda - maybe a new battery is the preferred solution.

15 hours ago, Cairus said:

Is the vehicle affected by the field measure where I think the gateway was the one that deeply discharged the 12V battery because it did not go to sleep

Mine had this issue, it would not discharge battery even overnight, not even mention in 10 minutes like in OP's case.

15 hours ago, OccyVRS said:

I've never really seen a battery die fully - there is always enough to at least make the alarm light flash or something.

Octavias are actually known to become completely dead when voltage drops, with no prior warning. Been there myself.

@Octawia can't really think what could be wrong in your case apart of defective battery, which coincidentally died at exactly this moment after being loaded by central lock. Does not seem too probable, but again, tons of cars with defective batteries out there, and I can't think so far of another explanation. I would check battery voltage first thing.
Also, it is not such a big of a problem to tow the car from underground, unless it is some extremely tight spot. Pickup truck picks the front, rollers under the rear wheels and here we go.

Hi @Octawia ,

The same thing happened to me a month ago during our family vacation...

In my case, it was perhaps even worse because the car did not respond to the keys (I could not unlock it), and I had to unlock it mechanically!

I won't describe the whole situation, but it was a big hassle.

The problem for me was that the car's computer "went to sleep" for some reason, bearing in mind that I had been driving the car an hour earlier!

The solution, after I had tried everything else, We even supplied power from another car... To disconnect one of the two terminals of the 12V battery and after 5 minutes to reconnect it and the car started/Glow like christmas tree 🙂 I was very happy about that 😁

I went to the Skoda dealer a few days later and they told me that the problem was that the computer was going to sleep. After diagnosing the car, Skoda has a TPI, I think it's called, for the problem. The solution is to update several modules in the car.

I'm not saying that this is the problem with yours, but it's quite possible that it is. Go to a dealer to have the car checked out.

The service arrived this morning and we jump started it. It's definitely related to the 12V battery or it's related circuits.

As the PHEV always starts in EV mode by default, I actually found a way of over-riding it. Press the brake and the accelerator in the same time, press the start button, then the petrol engine starts. Try not to over press the accelerator as you may fry the turbo at start. Then let it run at idle.

I also found out that the only way to recharge the 12V battery is by recuperation as these cars don't have the traditional alternators anymore. So, if your battery has drained for some reason, you need to drive it around like an hour or so. That kinda sucks.

I've been reading a lot other discussions regarding the battery on the Octavia 4 PHEV TSI Combi and it seems like this is a common glitch with the Skoda PHEVs. I'm calling it "Skoda PHEVs" not VW because apparently Skoda has placed in more electronic stuff compared to VW models, causing it to drain faster; I never had a problem with my T-ROC before. So, whatever you do, the 12V battery doesn't recharge enough and eventually it will drain empty until a poor soul like me gets stuck. (This also may explain why it was a bargain🤦‍♂️)

I've driven it around for an hour but when I switched off the engine, boom! it all went again for the 2nd time!! 😭. So, I will now call the Skoda road assistance one more time. This time at least I can leave it at home until I get an appointment from a service (in Finland, service stations are always booked, probably give me an appointment for 10 days or more later).

I found this video on Youtube, which explains the problem and less of the solution Hybrid 12v Battery Care - The Truth About The Hybrid 12V Battery Problem: What You Need to Know - YouTube

4 minutes ago, Octawia said:

only way to recharge the 12V battery is by recuperation

I can hardly imagine...