Yesterday, on the way back from work, my car suddenly had a stop start error and the EPC light came on, the car functions completely normal and there's no difference in how it was driving before...

My friend used a obd2 scanner which showed no fault codes on the ECU, cleared it and the light and error went away, I drove a bit and there are no lights or errors on the car, I was just wondering what could have caused this as online it says anything from turbo waste gate or actuator problems to a dodgy battery

I once had a start/stop error happen because of a dodgy LED brake light I had fitted. Anything can cause the BCM to have a meltdown.

If you had the EPC light on, you MUST have had a fault code stored. You say your friend "cleared it", well, they cleared the stored code which causes the EPC light to turn on..

You are best monitoring it, if the light comes back then scan every module in the vehicle and pop back with all the codes, regardless of how small they may be.

If not, consider it a momentary blip..

Not usually dodgy battery but one that has been perhaps over used, abused or neglected. Doesn't take very long or much effort to check the state of charge of the battery and whilst doing that check the battery post terminal and terminal post clamps are clean and tight, check main earths and connections are also clean and tight.

If battery needs charging then a good long drive without using much electrics or better still a full, long, low, recharge using an appropriate battery charger maintainer following the instructions in the car's 'Owner's manual' and instructions for charger maintainer. VWŠkoda website for "virtual"(?) 'Owner's manual'. - https://www.skoda-auto.com/apps/manuals/Models

You are dealing with German (over?) complex and (over?) intwined computer systems and programs on the car that will have errors and omissions, "glitches" and updates in the programming and computers can have brain-farts as we know. If your car is a late 2020 perhaps Covid and chip shortages might also apply< i forget dates and details now.

The computer system run on 5v which is thin so if battery is low, but headlights can still seem bright enough and engine starts, the computers can throw up all sorts of warnings, lights, (error codes) and issues, loads and loads of threads and posts on this problem on this site.

If you are lucky this could just be a one-off computer brain-fart and perhaps having switched the ignition "off 'n' on agen" cleared it, fills one with joy, if not over-confident about computer system perhaps.

Edited 19 April, 20251 yr by nta16
typo

Just want to add to this great suggestion;

15 minutes ago, nta16 said:

If battery needs charging then a good long drive without using much electrics

A good long drive with the start/stop disable button illuminated orange. When the disable button is actived it overrides any and all "smart" systems controlling battery levels and will just, simply charge.

Up until last year I had the same battery from factory in, which started to fail. It started setting off my car alarm in the dead of the night, yet the car would start fine. The battery can indeed do mysterious things..

1 hour ago, lewiswal47 said:

Just want to add to this great suggestion;

A good long drive with the start/stop disable button illuminated orange. When the disable button is actived it overrides any and all "smart" systems controlling battery levels and will just, simply charge.

Up until last year I had the same battery from factory in, which started to fail. It started setting off my car alarm in the dead of the night, yet the car would start fine. The battery can indeed do mysterious things..

4 hours ago, lewiswal47 said:

I once had a start/stop error happen because of a dodgy LED brake light I had fitted. Anything can cause the BCM to have a meltdown.

If you had the EPC light on, you MUST have had a fault code stored. You say your friend "cleared it", well, they cleared the stored code which causes the EPC light to turn on..

You are best monitoring it, if the light comes back then scan every module in the vehicle and pop back with all the codes, regardless of how small they may be.

If not, consider it a momentary blip..

Thank you. I will definitely continue to monitor it

1 hour ago, nta16 said:

No t usually dodgy battery but one that has been perhaps over used, abused or neglected. Doesn't take very long or much effort to check the state of charge of the battery and whilst doing that check the battery post terminal and terminal post clamps are clean and tight, check main earths and connections are also clean and tight.

If battery needs charging then a good long drive without using much electrics or better still a full, long, low, recharge using an appropriate battery charger maintainer following the instructions in the car's 'Owner's manual' and instructions for charger maintainer. VWŠkoda website for "virtual"(?) 'Owner's manual'. - https://www.skoda-auto.com/apps/manuals/Models

You are dealing with German (over?) complex and (over?) intwined computer systems and programs on the car that will have errors and omissions, "glitches" and updates in the programming and computers can have brain-farts as we know. If your car is a late 2020 perhaps Covid and chip shortages might also apply< i forget dates and details now.

The computer system run on 5v which is thin so if battery is low, but headlights can still seem bright enough and engine starts, the computers can throw up all sorts of warnings, lights, (error codes) and issues, loads and loads of threads and posts on this problem on this site.

If you are lucky this could just be a one-off computer brain-fart and perhaps having switched the ignition "off 'n' on agen" cleared it, fills one with joy, if not over-confident about computer system perhaps.

My car was first registered August 2020, I am going to get the battery inspected today , thank you

3 hours ago, lewiswal47 said:

It started setting off my car alarm in the dead of the night, yet the car would start fine. The battery can indeed do mysterious things..

My stalking troll and other insisted the car 12v battery wouldn't do this as the alarm has it's own battery, failing to fully appreciate the alarm and other computer systems on the car. I warned a Porker owner in the club about this many years back as his neighbours weren't too keen about the car alarm going off at 3 am. Then next year's tour another Porker owner with same thing, suggested 12v car battery to him too. And 10 years ago I was helping push a different newish Porker as the battery was totally down because the owner didn't want to pay the (overpriced) cost of a Porker "dedicated" 12v battery from Porker pens - but he should have known better being a long time Westfield owner. I've never owned a Porsche myself.

Edited 19 April, 20251 yr by nta16
typos

I got the battery checked at 69% health, it hasn't come back since but as soon as I finished work and was on the way home, I turned the ac on full and that's when it happened..I might just chalk it down to electrical gremlins and keep an eye on it

69% health still needs a good level of state of charge, a brand new battery can be "flat" - but in my mind a 2020 VW car is even more of a candidate for electric/electronic, computer systems/program issues. Program updates?

I always promote preventative car battery charging, very occasionally full recharging with appropriate charger maintainer or as required, prevention is better than cure and that way you should get better and (much) longer useable service from the battery and not become a statistic in the No. 1 cause of recovery breakdown callouts.

Of course we haven't covered if the car has had full and timely "service" and "maintenance" as per VW's schedule (minimal though they are), has the car had all its annual engine oil and filter changes done on time/distance, engine air filter changed (and perhaps airbox and ducting cleaned), a good possibly for issues have the spark plugs been changed.

I think it's 2019 Fabias with the throttle bodies that play up, might be 2020, I forget, and it might depend if early or late 2020.

But it might just be a one-off. If it happens again as already put a full scan tool health report might help plus if possible live data can be very useful.

For best results your friend's reader/scan tool does need to have a program on it appropriate to VW and your model and year (or VIN) and this program should be up to date before use on your car (some folk are too lazy to bother) and a reasonable state of charge on the car's 12v battery is required, and if appropriate a reasonable state of charge to the scan tool battery, otherwise out of date programs and low battery charge(s) can give spurious readings and results.

Good luck, let us know how you get on.

2 hours ago, nta16 said:

69% health still needs a good level of state of charge, a brand new battery can be "flat" - but in my mind a 2020 VW car is even more of a candidate for electric/electronic, computer systems/program issues. Program updates?

I always promote preventative car battery charging, very occasionally full recharging with appropriate charger maintainer or as required, prevention is better than cure and that way you should get better and (much) longer useable service from the battery and not become a statistic in the No. 1 cause of recovery breakdown callouts.

Of course we haven't covered if the car has had full and timely "service" and "maintenance" as per VW's schedule (minimal though they are), has the car had all its annual engine oil and filter changes done on time/distance, engine air filter changed (and perhaps airbox and ducting cleaned), a good possibly for issues have the spark plugs been changed.

I think it's 2019 Fabias with the throttle bodies that play up, might be 2020, I forget, and it might depend if early or late 2020.

But it might just be a one-off. If it happens again as already put a full scan tool health report might help plus if possible live data can be very useful.

For best results your friend's reader/scan tool does need to have a program on it appropriate to VW and your model and year (or VIN) and this program should be up to date before use on your car (some folk are too lazy to bother) and a reasonable state of charge on the car's 12v battery is required, and if appropriate a reasonable state of charge to the scan tool battery, otherwise out of date programs and low battery charge(s) can give spurious readings and results.

Good luck, let us know how you get on.

Thanks mate. Yeah all servicing is up to date but will be going for a major service in August. I think it doesn't help that I've had to do lots of short journeys lately

All the "services" now don't really service the engine let alone the whole car with the more important systems like brakes, steering, suspension (all three include tyres), safety electrics, (lights, wipers, blower horn, etc.), windows and mirrors (and reflective number plates) - see and be seen. The "maintenance" schedule fills in a few missing bits with engine and rest of the car.

Lots of short journeys doesn't help the engine much if the engine oil isn't getting warm enough, you want to be at say 90c engine oil temperature for a little while at least. Better to have your dash set so you can see the engine oil temperature rather than relying on the coolant gauge that's biased to show 90c before and after actually being 90c.

For the battery charging short journeys, particularly with more use of all the various bits on the car the car and driver and passenger(s) use will eventually help to deplete the battery's store sometimes to a point that upsets the car's computer systems. As it's (usually) so simple hands off (clean hands too) work to put a battery charger maintainer on the car to fully recharge the battery. If the battery is particularly low it can take many hours to recharge so overnight and a second or third session may be necessary, depending on how long can be given each time. But it's the easiest work on a car.

This is my wife's car one cold winter's night, I was inside warm and doing anything other than farting about with a car and a lot of the time asleep in bed. IIRC it took 14 hours with a 4-amp charger maintainer connecting on "winter" (5c and below) setting at lowest -4c that night, plus about another hour or so next day as the car had to be used for the very short journey to and from work interrupting the battery getting to full (or 'FUL' on that charger). And the battery wasn't even that low, just prevention.

9 hours ago, lewiswal47 said:

A good long drive with the start/stop disable button illuminated orange. When the disable button is activated it overrides any and all "smart" systems controlling battery levels and will just, simply charge.

This just stops the stop/start working.

The smart charging part is still operating as normal.

9 hours ago, nta16 said:

The computer system run on 5v

Which one runs on 5V?

Thanks. AG Falco

5 hours ago, AGFalco said:

This just stops the stop/start working.

The smart charging part is still operating as normal.

Yes but the "smart" alternator doesn't do too much when the engine's not running, and when the engine's not running electric power comes from the battery which after all is one of it's jobs but a 2020 VW will have a list of possible electric stuff as long as my short arms and legs combined some, much, could be being used whilst waiting stationary.

5 hours ago, AGFalco said:

Which one runs on 5V?

I was meaning the 5v reference for the little darlings, checking all's tickety-boo.

On 19/04/2025 at 18:08, AGFalco said:

This just stops the stop/start working.

The smart charging part is still operating as normal.

Interesting, I was told by somebody from Skoda that the button will change this - obviously this may not be the case it seems.

I would have thought that when stop/start is disabled the car may allow the battery to charge more fully, because it no longer needs to maintain a buffer for restart events.

I have often found better battery charge when driving with S/S Disabled compared to when its enabled (but not functioning); perhaps these are just coincidence?

I'll take some readings later through obd11 to see if the voltage really is any different with it on vs off!

@lewiswal47 have the following pdfs for some delightful reading (note how far back they're from).

Same as engine (and transmission) oil, for battery and battery charging there are camps of beliefs, sometimes strongly held.

SSP-234-Vehicle-batteries.pdf

SSP-426-Start-stop-system-2009.pdf

SSP-504_Vehicle_Batteries.pdf

ETA: Just been posting about OBDeleven (I use the letters instead of numbers to save confusion with OBD2 at a quick look/glance/read) I have seen some scan tool users post caution against the use of one-click how do you find OBDeleven for one-click programming/use, has it balls'd anything up for you?

48 minutes ago, nta16 said:

@lewiswal47 have the following pdfs for some delightful reading (note how far back they're from).

Same as engine (and transmission) oil, for battery and battery charging there are camps of beliefs, sometimes strongly held.

SSP-234-Vehicle-batteries.pdf

SSP-426-Start-stop-system-2009.pdf

SSP-504_Vehicle_Batteries.pdf

Interesting, thank you! Ill take a read.

43 minutes ago, nta16 said:

has it balls'd anything up for you?

I have the PRO subscription and as such I do all the coding and adaptations myself, however I did try one One Click App maybe 2 year ago for "Urban Pace Joker Lights" and it epically failed, just threw up some light errors on my dash - so i just reverted it. I've never heard anybody say to me a OCA has ruined their car.

EDIT: The issue is that cars of the same model can have different variaties of everything, but usually the same BCM so the coding would exist and be accepted by it. Most OCA's will specify what you require for it to work but some don't - so a person unknowledged on their car may perhaps use an app for comfort opening of their sunroof, when they infact dont have one. But the app'll work!

Edited 21 April, 20251 yr by lewiswal47

Pressing the "auto Stop/Start" button seems to do nothing more than "what it says on the label" battery charging will remain to be limited to when the car is being "driven/powered" along to be only as little as necessary, on the "overrun/unpowered" as much wasted energy as possible will get converted into cramming charge back into the battery to reduce waste/emissions. I (still) seem to glance at my 12V DVM frequently to see "what is going on".

Especially on older cars, the health of the battery did tend to dictate how troublesome the car was - I had a 1991 Vauxhall Cav GSI 2000 16V 4X4 (yes all that was on plates on the rear end), its car alarm system was a bit too sensitive or just badly designed, when the car's 12V battery was more than 4 years old, the alarm tended to do off frequently. Replacing the battery solved that for the next 4 or 5 years, a bit annoying but proved to be an easy fix!

To avoid changing the battery too early, or just to monitor things after the first "false alarm", I fitted a low value fuse in line with the alarm system, when the system was working, if you placed your ear close to the windscreen end of the LHS of the bonnet, you would hear a ticking, like a heart beat - that would be a very low voltage pulse getting sent out to the alarm horn - if there was no very quiet ticking, I knew that the alarm had gone off and blown that fuse - so I quickly managed to disturbance down to a minimum, while making sure that that car was safe to leave parked when away from home, I'd only use the inline fuse when it was only being used for commuting and in a very secure company car park - which was probably 90% of its life, like my current car, only used for longer trips away and holidays - wife's car gets used for all local use.

3 hours ago, lewiswal47 said:

I've never heard anybody say to me a OCA has ruined their car.

I'd never heard of OCA. 😄 I can't remember details now but I think it was the one-click operations could balls-up the operation of that particular item, which I suppose could be quite serious depending on what it was /did. Might also be related to me disliking the look of the ancient nerdy, legacy, looking presentation of VCDS with it's long winded processes. Yes there might be joy in remembering what's where in all the different screens and boxes and fun and adventure of finding your way through but I've not got the best memory and never played computer games or done programming or any good at maths, all my detriment (well perhaps not the computer gaming) and those that can and enjoy it I'm happy for them but I prefer things simple and quick with computers and cars. If it ain't on a mouse right-click menu I'll probably forget how to get it done. Plus I'm not good at reading, writing, data entry, recognising errors in numbers, I confuse opposites - but apart from that . . . 😄

The one thing I would like possibly released from restraint by the computer program is to have the window winders live without the need for key in and ignition on (I prefer hand crank anyway, less weight, less to go wrong) as I can't stand getting into a parked car with solar heated cabin to high temperature and no fresh air. It used to be you never needed to lock a Škoda. 😄

Edited 21 April, 20251 yr by nta16
typos

1 hour ago, nta16 said:

I'd never heard of OCA. 😄 I can't remember details now but I think it was the one-click operations could balls-up the operation of that particular item, which I suppose could be quite serious depending on what it was /did. Might also be related to me disliking the look of the ancient nerdy, legacy, looking presentation of VCDS with it's long winded processes. Yes there might be joy in remembering what's where in all the different screens and boxes and fun and adventure of finding your way through but I've not got the best memory and never played computer games or done programming or any good at maths, all my detriment (well perhaps not the computer gaming) and those that can and enjoy it I'm happy for them but I prefer things simple and quick with computers and cars. If it ain't on a mouse right-click menu I'll probably forget how to get it done. Plus I'm not good at reading, writing, data entry, recognising errors in numbers, I confuse opposites - but apart from that . . . 😄

The one thing I would like possibly released from restraint by the computer program is to have the window winders live without the need for key in and ignition on (I prefer hand crank anyway, less weight, less to go wrong) as I can't stand getting into a parked car with solar heated cabin to high temperature and no fresh air. It used to be you never needed to lock a Škoda. 😄

By OCA i’m just referring to the One Click Apps offered by OBDeleven.

The apps are just submitted by the community to the developers and they publish them - It’s unlikely OBDeleven have a fleet of every VWAG vehicle to test them on so they’ll just get released I’d imagine; and also be copied/pasted from similar platforms as an “it might work”

I suppose if there’s nothing you really need to code then you don’t actually need to know it, or as you say, learn the VCDS way of life. But if you need specifics somebody here will (usually) always know how to do so!

Providing there’s the ability to resort the coding done by the apps there shouldn’t be any lasting damage caused to any components! ☺️

24 minutes ago, lewiswal47 said:

By OCA i’m just referring to the One Click Apps offered by OBDeleven.

Of course when I Googled it that wasn't the definition I found for programming but something that on Googling again I couldn't find ( ! ) but listed was https://support.obdeleven.com/en/articles/5627138-what-is-one-click-apps-oca-builder-and-how-to-use-it (these computers just like messing me around.

When I referred to them of wasn't thinking of OBDeleven particularly but other scan tool programs that are more straight forward than VCDS. I know of the "try this" scanner user forums and programs and of course it's a "try this - at your own risk and do a back-up to restore to before doing any alterations".

You probably already know that Briskoda has threads and posts, or links, for such stuff for OBDeleven and VCDS, found in 'Diagnostics & VCDS' forum and individual model forums.

'Diagnostics & VCDS' - https://www.briskoda.net/forums/forum/23-diagnostics-amp-vcds/

ETA: I forgot to post the Fabia Mk3 thread. - The Definitive VCDS / OBD11 / Carista list for the Fabia III - https://www.briskoda.net/forums/topic/492377-the-definitive-vcds-obd11-carista-list-for-the-fabia-iii

Light has come on again after a day of not driving, same thing, got to driving, turned the AC on and the amber EPC light was on and stop start error. Will be going for a diagnostic on tuesday