HI, I wonder if this rings any bells for anyone with a similar age car.

I have a wonderful Octavia estate which has given just over 100,000 miles of trouble free motoring. Recently we were coming back from another camping trip in Normandy.

We were heavily laden with camping gear, roof box (including camping chairs strapped to the outside of the box which would have significantly reduced the aerodynamics) and 2 adults and two teen passengers. AKA a good heavy load and a good workout on fast French auto-routes.

As we were getting closer to Calais I noticed the car occasionally "stutter" by which I mean it felt like an mis fire and a very brief (less than a second) complete loss of power. This occurred most when I was trying to maintain full speed as the road began to rise (and the engine was doing more work). I backed off and got into the slow lane for any hills but noticed it happening increasingly as the journey wore on (sometimes even on the flat if I was overtaking at higher speeds). We were on the clock to get to Calais for our ferry and had had a warning from P and IO. that the port was busy and they were advising to arrive early. So we didn't want to stop and let the car cool down but I backed off as much I as I could. Despite this as we got closer to calais I noticed the power dropping further and I found my self having to drop down the gears for even relatively small inclines.

We got across the channel but the problems persisted, even after a 90 minute cool off on the ferry. We had about another 90 mins driving to get home in the UK but the problem didn't feel worthy of calling out green flag so we limped back home.

At some point on the auto route the EPC warning light came on and stayed on until we got back to UK.

The next day I tested the car (unladen with just myself in it). it was much better and the power was back up. The EPC light had gone off but interestingly when I first turned the ignition it gave a message about a fault with the auto start system.

As I say the power was back up but I found if I tested the car by accelerating up a relatively steep hill I could still make it stutter/misfire.

I tried turning off the auto start system but found I could still get the stutter with this off (it is on by default on the car until you manually switch it off).

Since then I have down one or two short trips in the car. It seems fine again now on short trips...

This morning I did a short test (admittedly slower speeds) but on short hills accelerating hard it wasn't possible to make the car stutter at all (wither with auto start on or off).

Also the auto start fault message has not been seen since (either on ignition or at any other time).

A friend at work has a Volkswagen error code reader (hopefully compatible with my Skoda) which I'm hoping may give me some more info to work off and can hopefully pick up next week.

We have another camping trip down to the south west so 3-4 hours drive at the end of the month. I'm keen to get to the bottom of this.

I work in electronics so know what a buG£er trouble shooting intermittent faults can be so happy to hear anyone's tales of similar woes. I am reluctant to take the car to a garage until I have more of an understanding on what the problem is or could be based on some horror stories on this forum of folk taking cars to garages and being quoted silly money to replace things like turbos when the fault was actually much simpler...

It feels like a fault with the engine management of some description though either the unit itself or something elsewhere on the car which is causing the system to drop power to protect itself etc...

Grateful for any advice!

Well, first things first - its time to get a scan of the car.

I suggest investing in an ODBEleven system and if you can afford it, get the PRO subscription (helps you make coding changes etc).

https://obdeleven.com/products

That will give you the output from the ECU and different modules which should give you a lead on the issue. EPC - mean Electronic Power Control, i.e. the car is restricting its output for some reason.

First things first: Radiators. Can you make sure that your radiator is clean and has good airflow? Wash it the coolant package with a hosepipe (open up bonnet and clean it off as best as possible)

Second: Coolant. When was the last time your car had a coolant change? Should really be done every 5 years. Forget the "coolant for life" mantra. Also remove the Silica bag from the header tank and make sure it hasn't split. If it has, then you need a FULL flush (4-6 full flushes) to get rid of the silica as it would have blocked up EVERYTHING including the coolant channels in the engine block.

Third: Electronics - make sure one of your coil packs isn't dying. Ideally should be replaced every 100,000miles as a set of 4. Use Bosch or OEM parts here. Using ODBEleven will show you misfire counters.

Fourth: Airflow - undo the 8 screws from the air box and make sure that the air filter is nice and clean and hoover out any crud in the airbox.

When you were experiencing the issue with the loss of power in France, did you notice the temperature creep above the 90C mark on the dash?

Other things to check: oil - make sure to check the oil is at the correct level and hopefully you have a service of the last oil and filter change on the car. Should be running VAG 504/507 spec oil (5W30)

Hello, welcome to the forum.

From your description, it sounds as if you have a misfire under load - have the spark plugs been checked? Do you know if they have ever been changed?

A DTC scan should show high misfire counts if faulty plugs or coil packs are the cause.

Misfires can cause the EPC indicator to light up - Stop/Start will be inhibited when EPC is lit.

Edited 7 August, 20257 Aug by Warrior193
added information

Sometimes there are no Fault Codes logged for Spark Plug misfires if not enough in a cycle.

But regardless the plugs need taken out and inspected regardless of faults logged or not.

& the air filter inspected.

Maybe nothing relevant but was it E5 95 ron Petrol abroad, and was the last fill up nothing to cause concern.

Does it get E10 95 ron in the UK or E5 97 or 99 ron min?

Turbo actuator seized?

8 hours ago, varaderoguy said:

Well, first things first - its time to get a scan of the car.

I suggest investing in an ODBEleven system and if you can afford it, get the PRO subscription (helps you make coding changes etc).

https://obdeleven.com/products

That will give you the output from the ECU and different modules which should give you a lead on the issue. EPC - mean Electronic Power Control, i.e. the car is restricting its output for some reason.

First things first: Radiators. Can you make sure that your radiator is clean and has good airflow? Wash it the coolant package with a hosepipe (open up bonnet and clean it off as best as possible)

Second: Coolant. When was the last time your car had a coolant change? Should really be done every 5 years. Forget the "coolant for life" mantra. Also remove the Silica bag from the header tank and make sure it hasn't split. If it has, then you need a FULL flush (4-6 full flushes) to get rid of the silica as it would have blocked up EVERYTHING including the coolant channels in the engine block.

Third: Electronics - make sure one of your coil packs isn't dying. Ideally should be replaced every 100,000miles as a set of 4. Use Bosch or OEM parts here. Using ODBEleven will show you misfire counters.

Fourth: Airflow - undo the 8 screws from the air box and make sure that the air filter is nice and clean and hoover out any crud in the airbox.

When you were experiencing the issue with the loss of power in France, did you notice the temperature creep above the 90C mark on the dash?

Other things to check: oil - make sure to check the oil is at the correct level and hopefully you have a service of the last oil and filter change on the car. Should be running VAG 504/507 spec oil (5W30)

Thanks everyone for all this info. Will find out if my colleagues Error code reader is an ODBEleven.

It should be said that to date the car has always been serviced by Underwood's Skoda in Sudbury Suffolk. It was last serviced on the 25th of April if IO can find the paper work I can see which of the lists of tasks above have been done but I'd assume any routine maintenance, filter changes and fluid changes would be part of their regime.

Spark plugs does sound like a smoking gun though so I'll try and check them out!

17 hours ago, Ootohere said:

Sometimes there are no Fault Codes logged for Spark Plug misfires if not enough in a cycle.

But regardless the plugs need taken out and inspected regardless of faults logged or not.

& the air filter inspected.

Maybe nothing relevant but was it E5 95 ron Petrol abroad, and was the last fill up nothing to cause concern.

Does it get E10 95 ron in the UK or E5 97 or 99 ron min?

To be honest I always have used 95 RON both home and abroad. Perhaps it’s worth using the expensive stuff for long runs like this with a heavy load?

11 hours ago, MidfieldGeneral said:

It should be said that to date the car has always been serviced by Underwood's Skoda in Sudbury Suffolk

Yerr - I would probably look at not taking it to a Skoda dealer. If you honestly saw some of the completely underwhelming stuff that Škoda dealers do in terms of maintenance, you would be concerned. Go to a VAG specialist. There's one in Ipswich on the Woodbridge Road called VW Audi Workshop Ltd who would probably give you a far better service (although this is not an endorsement of any one place over another).

Spark plugs and coils - a good starting place to check.

11 hours ago, MidfieldGeneral said:

assume any routine maintenance, filter changes and fluid changes

What do they say about Assumptions? Don't assume that any main dealer has actually done anything that they've said they've done. I'm not saying that Underwoods are rogue, but in these days when dealers are not really interested in maintaining your loyalty or actually doing the servicing they are paid (handsomely to do), it is sometimes better to get a second opinion if your car is misbehaving.

2 hours ago, MidfieldGeneral said:

I always have used 95 RON both home and abroad

I would definitely start using 97 RON or an octane booster in the fuel to improve the burn cycle and improve performance.

My Personal recommendation is to use https://www.hydra-int.com/petrol-power-blast.html (and before this starts a flame war, its only my personal recommendation - I've found that it works for me). That way you can still use standard 95 RON but keep the EGR and Injectors nice and clean.

Codes need reading before you start playing the parts replacement roulette game.

I'd be suspecting coil packs - that can be affected by heat on a hard run. If these are changed it's also worth fitting new plugs.

However I have encountered similar symptoms though with a friends 1.8 tsi Yeti. Loosing power under load/ uphill. It was the High Pressure fuel pump.

Mrs Gaz's Polo GTI (1.8TSI) had a barely discernible misfire, which turned out to be a failing coil pack - a diagnostic scan revealed which one. It was an easy fix once we knew what it was. It flagged up as it got worse, triggering the EPC light.

The car is rarely under any load, with usually only one person in it, but I could see it being far more noticeable had it been loaded up like yours.

Our petrol cars are run pretty much exclusively on Momentum 99 👍. I've seen so many people say it doesn't notice whether 95 or 99RON is used, but I'm darn sure I can notice; moreso when giving it the beans.

Gaz

11 hours ago, Gaz said:

Our petrol cars are run pretty much exclusively on Momentum 99 👍. I've seen so many people say it doesn't notice whether 95 or 99RON is used, but I'm darn sure I can notice; moreso when giving it the beans.

Yup, with my old Superb II 1.4tsi it noticeably ran better on Momentum 99 from Tesco but made little difference to the economy.

However with the replacement Swace (Toyota Corolla TS gubbins) there is no discernible difference with the higher octane petrol.

Edited 8 August, 20258 Aug by bigjohn

13 hours ago, bigjohn said:

However with the replacement Swace (Toyota Corolla TS gubbins) there is no discernible difference with the higher octane petrol.

Not all engines have factory mapping that allows them to take advantage of higher octane fuel.

As to the 95 ron unleaded, E10 in the UK but maybe the car got E5 on continental Europe.

But then 95 ron is the Min octane, just as 97 or 99 E5 is in the UK,

Then they might not have 5% bio-ethanol or 10%. It is a location location location thing in the UK and by the seasons,

summer formulation and winter. As it is across the English Channel.

Sometimes the issue can be a higher octane or just more Additive / Detergents and doing the job and giving the system a bit of a clean out. carbon dislodged.

Sometimes a poor spark plug / poor gap that never shows with misfires can once the engine gets a nice Italian Tune up and nicer petrolum.

This was common with 1.4 TSI Twincharger, one dodgy plug and oiled and suited up.

Then use 99 octane E5 and the Exhaust Emissions or EPC light shows or both.

Likely not relevant, but it can be for some with issues.

http://briskoda.net/forums/topic/522389-e10-petrol-vs-e5-petrol

Edited 9 August, 20259 Aug by Ootohere

On 09/08/2025 at 12:11, PetrolDave said:

Not all engines have factory mapping that allows them to take advantage of higher octane fuel.

I think my Toyota based hybrid gubbins uses a different mapping altogether - Miller cycle? Can’t complain as it feels lively but still gets mid 60’s mpg.

Hello everyone. Firstly thank you to everyone for all the posts, suggestions and info. Apoloigies for the delayed reply. Work got really busy then we had a short break away (by plane).

I have been using the car though since getting back and it has now completed a couple of hour long commutes, all well under 50MPH it has to be said but its seems to be absolutely fine now (of course).

I am going to give it a longer run on Sunday with motorway speed and 4 passengers so that will be a good test.

I was able to borrow an RAC OBD compatible Fault code reader. Interestingly the reader showed NO Codes (See pictures attached).


Do the codes have a shelf life?

Does it delete codes if not viewed in a certain period?

My understanding is codes sit on the EMU until forcibly erased by a user with a tool (such as the one I was using). So if anything happened on the way back from France that the system noted it should be on there...

Based on a few of the posts my theory right now is drifting to fuelling. its perhaps no co-incidence that the car is much better since I fuelled it in the UK (admittedly with 95 RON, but good wholesome UK 95 RON, perhaps with no bio etheanol).

I am wondering if when I tanked up at the hypermarche using the automatic machine it may have been the 10% bio ethanol stuff. Add that to a long run, on a hot day, with a full load and lousy aerodynamics and high speeds and I was probably asking my poor 100,000 mile plus Octavia to go above and beyond the call of duty.

I am going to see how we run this weekend on a shortish trip to the south coast with two passengers and a few bags and then make sure the next couple of tanks (especially ahead of the next camping trip) are 98RON and see how that works out.

Oh for the record at the last service at Underwood's on 25th of April 2025 they actually did replace the spark plugs. So I think if we get this again hopefully we'll get an error code or two but for the moment I'm thinking maybe just misfiring as a result of the convergence of all those variables (a perfect storm perhaps). Will post back here if I get the fault again or the EPC light comes on again.

Not ruling out a coil pack but based on one of the posts above if it was that then theoretically we ought to see some codes...

@MidfieldGeneral Misfires might not be logged unless there is enough happening in a cycle.

So the lack of logged codes for mis-fires does not mean mis-fires were not felt when driving.

The continental 95 ron might have been E5 and not had up to 5% bio-ethanol.

UK 95 ron Unleaded is E10 and might have up to 10% bio-ethnol. OR Might not, well no more than 5%.

Where do you get 95 ron with no bio-ethanol in the UK?

Nobody sells 98 Ron petrol in the UK and have not for a decade and more, you get 97 or 99 ron minimum.

Edited 15 August, 202515 Aug by Ootohere

Thanks Ocotohere, Showing my ignorance here. A previous poster had mentioned fuel and differences with EU fuel as opposed to Uk fuel as a possible cause so I made assumptions about the degree to which bio ethanol is added as being the difference they were referring to.

Lets say that the fuel I bought in Europe was completely not the problem (as its quite possible). My thinking now though (given the problem has gone away, for now at least and the car is running on a set of near enough brand new spark plugs) is that the circumstances of that trip were causing the issues. I think then the heavy load the car was pulling might have more to do with the issues seen. So trying to look at all the things that were different that day>

Mainly thats:

The temperature (quite a warm day)
The distance (relatively long)
The load in weight (very high by normal standards, 4 passengers plus camping gear in boot and roof box)
Aerodynamics (compromised due to camping chairs strapped to roof bars in addition to roof box)
Speed (higher than normal as French speed limits higher)

Lets rule out fuel based on the very helpful info provided above.

There were definitely (what I would call) misfires so the system did not log them (for whatever reason). Would you agree that since the problem has gone away since getting back to England a sensible pre caution now would be to use more expensive petrol for a while or indeed a fuel additive as someone else has suggested on here?

I am thinking for the next fully loaded long run with camping gear (down from Essex borders to the south west) it might be a good precaution to fuel up with higher grade petrol.

Would that make sense to you?

Thanks again for your post.

Super informative. I had heard that all the major supermarkets and filling stations were essentially tended from the same refineries and fuel depots so the differences between higher and lower grade fuels that they advertise were more to do with marketing than real chemical differences.