Hi!

Octavia vRS TDI 2015 - For a while I've been experiencing constant DPF regens - the idle tick over constantly sits at 1K with the radiator fans running for a while after the ignition is turned off.

I drive motorway miles daily so it's not a symptom of short trips although on longer 2 trip ~2hrs the Particle Filter warning will appear but clears after ignition reset. I've noticed the regens are having a massive impact on fuel economy (only managing ~350 miles on a full tank when previously I could get around 400-420) as well as oil consumption.

I've had a local garage take a look and apparently found no fault and added a DPF additive to the fuel and told me to blast the car down the motorway - I interpret that as they couldn't be arsed to investigate it as they didn't even charge me...

Has anyone experienced a similar issue? I feel I'll need to point the garage at the potential causes as they're not going to find it on their own it seems...

Thanks!

Rather relevant is how many miles on the car. Have you not had a reading of the ash / oil ash content?

52 minutes ago, Evolution13 said:

Rather relevant is how many miles on the car. Have you not had a reading of the ash / oil ash content?

Mileage is ~132k and the garage reported the ash level to be around 60%.

My 2014 1.6 diesel doing similar and noticed a higher fuel consumption so wondering if i have an issue with the dpf however no warning light and my car is at 194k.

My mechanic was like yours when questioned him about the higer fuel consumption. Kinda out it down to age of car depsite me getting good mpg prior to service.

Fan didn't come on today despite doing small journeys but mpg was only 33 where other times mpg has been 50or so

Edited 20 June20 Jun by chrisski

vRS has the 184hp CUNA engine, right?

If so, how's your oil consumption? These engines LOVE to drink and burn oil. This can result in the DPF clogging prematurely. If you have excessive oil consumption (more than 1L per 1000km), then it could be your turbo as well.

However, if its the 184hp engine and you do have notable oil consumption, I suspect your DPF is just full and needs physical cleaning or even replacing.

On 20/06/2026 at 18:32, viper42 said:

vRS has the 184hp CUNA engine, right?

If so, how's your oil consumption? These engines LOVE to drink and burn oil. This can result in the DPF clogging prematurely. If you have excessive oil consumption (more than 1L per 1000km), then it could be your turbo as well.

However, if its the 184hp engine and you do have notable oil consumption, I suspect your DPF is just full and needs physical cleaning or even replacing.

Yes, it's the CUNA 184. It's currently in the garage and the mechanic is struggling to find any issues!

Constant regens, reduced range, 1l of oil per 600 miles and can't find a problem smh

Usual suspects on the CUNA are the piston rings, specifically the oil rings that like to clog form long-life oil services. They coke up with oil coal and get clogged. That way the oil that would otherwise just be "wiped" away now gets burnt. Most of the time you can't chemically clean them anymore, so you actually need to pull the pistons and replace the rings. Then hope that the cylinder walls still look alright.

The other mentioned suspect would be the turbo, depending on the mileage and how its been driven. However the piston rings are a common thing on the CUNA.

The CUNA specifically really is a horribly designed engine when it comes to that. Poor thermals and pistons oil rings that have holes that are too small and like to clog easily. Mix that with the poor thermals and long-life services and you get this as a result. Its basically the entire 1st gen EA888 1.8 TFSI story all over again.

So that would explain the high oil consumption. Do you think the DPF regen issue is totally unrelated?