[ctjithinkrishna]

I bought a used 2018 Skoda Octavia VRS in November 2024. It was seemingly well maintained and had run 58k kms. I had also taken it to Skoda for an inspection which it passed with 0 issues. The owner told me that it has a stage 1 Venom performance remap on the ECU. He was not sure about the TCU.

Fast forward to a month later, I was driving enthusiastically in sport mode. All was going well until a burning smell filled the cabin. The AC was on at the time. I immediately stopped the vehicle and opened the bonnet and I was confused to find that there was no smell in the engine bay or anywhere outside the car. That made me curious. I then drove with AC on and off separately and discovered that the smell comes only when the AC is on. 1 or 2 days later, I started hearing a repetitive squeak when the AC is on. I took it to a reputed car garage here in Bengaluru and explained both the problems. They test drove the car to confirm the smell and the noise. The told me that the blower fan needs to be replaced and it was. Once the part arrived, I dropped the car for the replacement. Once the part was replaced, they called me up and said that the burning smell issue is now solved as they did not notice it when they test drove the car after the replacement. I was happy and I got the car back and since then I did not notice the smell for 1 to 2 months. And I thought the smell issue was solved.

But I was wrong, the smell came back again when I was driving it in sport mode again. I don't know why the smell did not come back earlier, maybe I did not push the car enough. Similar to before, the smell only comes in when the AC is on. I took it to the same garage again, they checked the car for 2 whole days and could not find any issue with the car, but they could recreate the smell easily. I was left perplexed. Then they called me up on the 3rd day to tell me that the smell was not coming anymore. They had unplugged and replugged the blower fan after which they could not notice the smell

I have since taken car back from the garage. But the smell came back the next day itself. Earlier, I could notice the smell only in high speeds in sport mode as I only drove in sport mode when I had open roads. But now I can smell it randomly in sport mode, even in slower speeds. Which makes me believe that the higher RPMs is what triggers the smell. I can also now rule out the AC intake flaps being pushed open by wind at higher speeds. I called up the garage, and they are now hypothesizing that there might be a coolant leak or some residue in the AC coil which is burning off to give out the smell?

I also did contact the shop who did the Venom remap and they claimed that most VRS's have this burning smell issue. My usual garage guy denies that claim as he owns a stage 3 VRS himself and have tuned multiple VRSs and have never came across this issue. I also learnt from Venom shop that the TCU had not been remapped.

Has anyone faced or heard about this issue? Could it be related to the fact that only the ECU has been remapped? Or could it be a simple AC residue issue?

[Jeroen]

Originally Posted by ctjithinkrishna

I also did contact the shop who did the Venom remap and they claimed that most VRS's have this burning smell issue

Well, let's make one thing clear. NO car, no matter what modifications or work have been carried out, should have a burning smell! Period!

It means something is not right.

Originally Posted by ctjithinkrishna

as anyone faced or heard about this issue? Could it be related to the fact that only the ECU has been remapped? Or could it be a simple AC residue issue?

I must admit your problems have baffled me, especially since the behaviour appears to be more or less completely random, albeit at higher RPMS currently.

I doubt it is a cooling liquid leak, as that would not burn.

I would at least try to isolate the problem from the engine bay and inside the cabin. So drive the car with all windows and all air vents and flaps completely shut. If you notice the smell, it means something inside the cabin is burning/smouldering. Which means diving under the dashboard.

If not, it is more likely to come from the engine bay or perhaps under the car, its exhaust system. But even so, it's curious that it finds its way into the cabin. That also means whatever it is must be near the air entry of the cabin air intake. That is usually on top of the cowling, so somehow, just below it there might be a problem.

So that's where I would start looking. Check for any visual signs.

I doubt it is any residual oil as that simply burns off and will stop.

There is one thing you might want to check as well. Most cabin air system have a resistor fitted that allows you to choose different fan speeds. That resistor typically sits inside one of the air ducts. Usually near the heater core.

It's the one electrical/electronic component that sticks inside the cabin air ducts. So if something is amiss, that might cause a burning smell.

For reference, here is the link to the one I replaced on my wife's Ford Fiesta

https://www.team-bhp.com/forum/diy-d...ml#post4516485 (My Car Hobby: Jaguar XJR, Mercedes W123, Alfa Romeo Spider, Jeep Cherokee & Mini One)

I would also do a very thorough inspection of the engine bay and the area around the exhaust. You are looking for telltale signs of burning. You might have a tiny hole somewhere that leaks a tiny bit of oil on something hot. Its tiny it simply burns off, but a few drops of oil burning can give a powerful smell.

Good luck. Let us know what you find.

Jeroen

[AMG Power]

When you drive cars enthusiastically, there is always a smell akin to burning when you open the hood which is due to the high temperatures in the engine bay.

However that should not permeate into the cabin. My assumption is that some of these fumes are being drawn into the cabin.

This could be due to recirculation flaps not closing properly, a leak between the several grommets on the firewall or just a plain gap that has developed in the various crevices on the firewall.

This is going to take some time to isolate. In the interim, find a workshop that does not rip you off and has better diagnostic capabilities than the last one. That will matter too.

[fordday]

Originally Posted by ctjithinkrishna

Then they called me up on the 3rd day to tell me that the smell was not coming anymore. They had unplugged and replugged the blower fan after which they could not notice the smell

Which workshop is this? We all need to know as many of us take it to FNG instead of service center.

[SS-Traveller]

Originally Posted by ctjithinkrishna

...burning smell filled the cabin.

Too many variables here, to pinpoint the source of the smell.

- sports mode: I presume the coolant temperature meter stayed normal. Would like to know the oil temperature reading then.

- AC on when smell occurs: what kind of smell? Oil burning, or wire / insulation burning? If AC is switched off, does the smell dissipate almost immediately, or lingers for a while? When driving in sports mode without AC, are the windows tightly shut or rolled down a bit?

- no smell after blower change: was the car not driven in sports mode soon after the blower change? Or did the smell occur a few weeks later, and no smell occurred in the interim despite driving in sports mode? Was there a burnt insulation smell from the old blower which was changed?

- higher rpm in sports mode = alternator over-voltage (AVR failure)? : just thinking aloud. May be worth checking. The higher voltage may be burning the blower motor or its speed controlling resistor again.

[ssjr0498]

This is most probably the cause. You might be experiencing a small leak from the valve cover gasket or from somewhere in the engine bay, which is accentuated when you do spirited runs! Have it check properly and also check your ac flaps/cabin air filter.

Originally Posted by Jeroen

I would also do a very thorough inspection of the engine bay and the area around the exhaust. You are looking for telltale signs of burning. You might have a tiny hole somewhere that leaks a tiny bit of oil on something hot. Its tiny it simply burns off, but a few drops of oil burning can give a powerful smell.

Good luck. Let us know what you find.

Jeroen

[dhanushs]

Since the car is remapped here, I'm suspecting the transmission. VW has very clear torque limitation maps, which also maximize the performance of the car and protect their components. First thing the guys who remap do is to remove all the torque limitation maps.

In your case I'm suspecting more torque to the clutch pack in the DSG and hence the smell.

If not, it can be the fluids leaking out and not leaving a residue and burning off. Check your manifold and exhaust system (basically all hot parts) for residue.

[ctjithinkrishna]

Originally Posted by Jeroen

It's the one electrical/electronic component that sticks inside the cabin air ducts. So if something is amiss, that might cause a burning smell.

Originally Posted by Jeroen

I would also do a very thorough inspection of the engine bay and the area around the exhaust. You are looking for telltale signs of burning. You might have a tiny hole somewhere that leaks a tiny bit of oil on something hot. Its tiny it simply burns off, but a few drops of oil burning can give a powerful smell.

Originally Posted by dhanushs

In your case I'm suspecting more torque to the clutch pack in the DSG and hence the smell.

Would it help to rev the car in Neutral to high RPMs and check for the smell? I am guessing that if a transmission issue, it won't cause a smell in N.

Originally Posted by SS-Traveller

Too many variables here, to pinpoint the source of the smell.

- sports mode: I presume the coolant temperature meter stayed normal. Would like to know the oil temperature reading then.

- AC on when smell occurs: what kind of smell? Oil burning, or wire / insulation burning? If AC is switched off, does the smell dissipate almost immediately, or lingers for a while? When driving in sports mode without AC, are the windows tightly shut or rolled down a bit?

- no smell after blower change: was the car not driven in sports mode soon after the blower change? Or did the smell occur a few weeks later, and no smell occurred in the interim despite driving in sports mode? Was there a burnt insulation smell from the old blower which was changed?

- higher rpm in sports mode = alternator over-voltage (AVR failure)? : just thinking aloud. May be worth checking. The higher voltage may be burning the blower motor or its speed controlling resistor again.

- Oil Temp: It was around 100 to 102 at that moment. Don't remember exactly, will check out. Above what temperature should I be worried?
- I am not sure. I feel like a mix of wire burning smell and a matchstick smell. Not very experienced with oil or coolant burning smell.
- Immediately after blower change, the garage said they drove in sport mode and reported no smell. But I could smell it the next day.

Originally Posted by AMG Power

In the interim, find a workshop that does not rip you off and has better diagnostic capabilities than the last one. That will matter too.

Can anyone suggest good garages in Bengaluru that might have some experience with Skoda and VRSs?

Thanks everyone for the help.

[IshaanIan]

Is there no dependable authorised service centre that you can take your car to? Usually when there is an issue with a car, taking it to the biggest ASC and meeting with the works manager tends to be the best route although I am not sure about Škoda’s operations in Bangalore as this requires that the brand have atleast one dependable and capable ASC available.

[GhatWanderer]

Relatable issue, although on my manual Rapid. The only time I experienced a distinct burning smell was during a tough uphill climb in bumper-to-bumper Darjeeling traffic.

Turned out to be a burnt clutch plate. Left me stranded for nearly 5 days as the nearest Skoda dealership (Siliguri) didn't have the overhaul kit readily available. Parts availability can be a challenge in remote areas.

While yours is a DSG, the smell under heavy load (high RPM/sport mode) might point towards the transmission's clutch packs getting stressed, perhaps exacerbated by the remap. Worth getting the DSG thoroughly checked, specifically for any signs of clutch slip or overheating under load.

[svsantosh]

1st question - Answer can go totally opposite ways in troubleshooting

Was your AC in Re-Circulate mode or Fresh air mode?

[ctjithinkrishna]

Originally Posted by svsantosh

1st question - Answer can go totally opposite ways in troubleshooting

Was your AC in Re-Circulate mode or Fresh air mode?

I was getting the smell in both modes.

[abaliga]

Originally Posted by ctjithinkrishna

Has anyone faced or heard about this issue? Could it be related to the fact that only the ECU has been remapped? Or could it be a simple AC residue issue?

While there could be many root causes for the reported issue; please do replace your cabin air filter, the air filter may have caught some ash and could be throwing the same smell.

I had a similar issue with my Octavia, but it was nothing to do with the car itself, there were some dry leaves burned near our house and the smoke from the same was diverted to the car's front section from the wind.

Until I replaced the cabin air filter, I could smell the ash every time I started the car. Also, it is recommended you get the vehicle scanned for error codes. Typically these vehicles have a log for any abnormal parameter reported by the engine, gearbox, brakes and sensors.

[praveen789]

Is it possible to get back to the stock map to check? It will help to isolate the issue if it is related to the remap pushing the limits of the DSG/engine causing the issue.

[RunSam]

Originally Posted by ctjithinkrishna

Can anyone suggest good garages in Bengaluru that might have some experience with Skoda and VRSs?

I would suggest getting in touch with Sharan from Vagmaster, as they are setting up shop in bangalore. They specialize in VAG cars mostly apart from other German cars