DPF regeneration frequency

[Calais62]

Apologies for yet another DPF question. I am still getting used to my 2019 Karoq 1.6 TDI , bought in December (subject of a previous post about Adblue issues.) Having searched through several posts about DPF issues, I cannot find what is considered to be a 'normal' frequency for regeneration. My journey pattern is mostly short trips around town with a 20 minute motorway drive once a week. The car is trying to regenerate every couple of days, even after a motorway trip at a constant 70 mph for 20 minutes. Can anyone advise me if this is normal or does it indicate a fault somewhere? My previous car, Peugeot 3008 1.6 diesel, never seemed to regenerate this frequently despite having a similar usage pattern.

[varooom]

There isn't really what I would say is a "normal" there just is regens based upon the amount of soot being generated, and the overall mileage of car has an impact as the DPF filter becomes less effective with age (talking a fair few miles though!)

 

Try having a read here

https://procarmanuals.com/pdf-online-vag-ssp-330-diesel-particulate-filter-system-additive/

 

You will find that on a motorway you will be doing most likely "passive" regeneration that is not as fast as an "active" regen.

If you are concerned, you may want to look into the DPF app that some get on their phone and hook up a device to the OBD port to broadcast the values to the app.

[SurreyJohn]

If your car is trying to regen every couple of days, then it thinks the previous one didn't finish the job, and still got more to do.

 

If it needs a catch-up then a 20 minute trip is far too short, probably looking at a 30 minute regen starting from when everything is hot enough.  Which on a cold winters day is likely to be 15-25 minutes.   So going to need at least 50 minutes use.    Once back to regular regens back to nearer 25 minutes (plus about 10 minutes extra in cold weather).

 

Without knowing the service or usage history, there is a chance previous owner did lots of short journeys too, if too many regens are incomplete tend to get an ash and soot build up which sort of bakes on and a regen won't ever fully clean.  As previous replies have said, can scan for the ash level which will give you indication of how clogged the DPF is.

 

Don't want to be bearer of bad news, but if too badly clogged will need a DPF clean, not cheap, and if only had it a few weeks best bet is to get supplying dealer to fix it as a fault developing at time of sale.

 

Your problem is if you mainly do town driving and only occasional other journeys then the emissions system on a euro6d diesel will keep giving problems.  A diesel doing a regen uses more fuel than a petrol.  So really you have bought the wrong car, and should have got the petrol version.   The diesel is not efficient on cold short journeys, diesels are best when warmed through, remember the WLTP fuel figures are tested at about +23c (and not during a regen).

 

I wouldn't compare it to an older diesel without latest emissions equipment, they didn't have to spend some of their life (and lots of extra fuel) cleaning and burning particles at high temperatures.  Diesels are now a liability if they are unable to fully regen because sensors limit things until they do to meet emissions requirements.

 

 

[Sanqhar]

Check your engine oil level. Regens are made by extra diesel being injected into the engine. If these regens don't burn off this diesel then it runs down the bores into the engine thus diluting and raising the oil level.  Not good.  If this has happened you will also need an oil change.

 

If a regen is occurring and you turn off the engine before it has finished the engine will be hot and often the cooling fan will remain running.  After "the fix" my 2010 diesel Yeti did this regularly.  I would then immediately restart and go for a decent 60/70 mph drive alternating between 3rd or 4th gear, not top gear, in order to burn off this extra diesel and complete the regeneration. 

 

Modern diesels are not designed for too many regular short journeys.  This was the reason that when my driving pattern changed I got rid of my Yeti and bought a petrol Karoq.  I am currently only doing around 5000 miles a year. 

 

tom 

 

Edited 29 January, 2023 by Sanqhar

[J.R.]

3 hours ago, SurreyJohn said:

The diesel is not efficient on cold short journeys, diesels are best when warmed through,

 

I agree with everything else you say but have to challenge the above.

Whilst all IC engines are at their most efficient when at normal operating temperature diesels are by far the most economical of all fuel types during the post start warm up cycle, once the compression ignition cycle is maintained, no more than a few seconds no enrichment of the mixture is needed, this is in stark contrast to petrol engines that need a much enriched air fuel ratio all the way through the warm up period.

 

I know the glowplugs on modern diesels remain on for a while after start up but that is for emissions, the engine is running compression ignition within seconds.

 

Modern post combustion emissions control equipment, EGR and DPF's are what have killed diesels from being the best for short journeys.

 

My last 3 diesel vehicles were returning 60mpg after 1 mile if I drove through the village at 50kph rather than up the hill and onto the faster main road, no less MPG in winter conditions after a cold start, a petrol engine would only return its maximum economy after 4 miles minimum, further in winter.

Edited 29 January, 2023 by J.R.

[Calais62]

Thanks for all your replies. Once again it shows that although everyone agrees in general about modern diesels, DPFs,  short journeys etc there is still debate about the regen process itself  ie  how far one needs to drive, at what speed and in which gear. When i bought the car, the salesperson advised 20 minutes in 4th but the issue now is that I am driving the car simply to regenerate the DPF with no other purpose for the journey. I think I will get the dealer to check the ash build up but I think I am going to take the financial hit due to depreciation and change to a petrol engine model.

[Routemaster1461]

Just for clarity, a DPF removes ash and soot from the exhaust gases. The soot is removed by the regeneration, often aided by a catalyst. In the case of PSA vehicles this is aided by injection of EOLYS fluid into the fuel tank. The fluid contains cerium compounds with lower the temperature requird to burn off the soot. I don't know whether VAG use a similar method, or whether it simply relys on getting the filter hotter.

 

The problem with DPFs is ash. Ash is formed from the sulphur and phosphorus compounds found in oil. This is why low SAPs oils are required. This is not now confined to diesels as most, if not all, very recent petrol cars are fitted with a GPF. The ash cannot be burned out of the filter, and this may autimately block the filtedr, requiring either removing the filter and cleaning or a replacement filter.

[varooom]

46 minutes ago, Routemaster1461 said:

Just for clarity, a DPF removes ash and soot from the exhaust gases.

You might want to edit that quickly if possible, to read "captures" as removes implies it literally removes it.  As you later go on to say, the Ash oil cannot be removed.

Edited 30 January, 2023 by varooom
spellink

[MATT0693]

I've seen my DPF regenerate in as little as 80miles, that is with loads of short trips not allowing the car to reach full operating temp.
I did a return trip to London on Saturday and it did 343miles between regens.. with mixed driving it is usually around 200miles between each. 

If your DPF health is already poor due to yours or the previous owners driving habits, the DPF will be less efficient and have to regen more often. 
I have the VAGDPF app, so I can monitor/check the DPF state, duration, distance etc - worth it for a couple of quid on the app store. If your figures all look ok then it could be an issue with a sensor, or just that your driving patterns don't suit the car. 

 

[Ootohere]

@MATT0693 is that your 2.0 TDI from 2016 and not a newer 1.6 TDI in a Karoq which Skoda discontinued? 

[SurreyJohn]

6 hours ago, Calais62 said:

Thanks for all your replies. Once again it shows that although everyone agrees in general about modern diesels, DPFs,  short journeys etc there is still debate about the regen process itself  ie  how far one needs to drive, at what speed and in which gear. When i bought the car, the salesperson advised 20 minutes in 4th but the issue now is that I am driving the car simply to regenerate the DPF with no other purpose for the journey. I think I will get the dealer to check the ash build up but I think I am going to take the financial hit due to depreciation and change to a petrol engine model.

You might be better using a mis-sold argument if the salesman misled you.  Whilst you might get nowhere, the old adage of if don't ask, won't get applies so no loss trying.

 

Similarly might be worth asking if they will take it back due to the DPF problem and source you a petrol version instead.  Again might not get anywhere, but if it does and you effectively share any financial hit, then better than you taking 100% of the hit.

 

Whilst it is too late for Op, just in case anyone else is reading this thread because thinking of buying a diesel Karoq, be very wary of any that might have been used for mainly local journeys during lockdown.  Try and see service intervals and mileages, a car that has done less than 10k miles over 3 years since first lockdown, might not have done many longer journeys

 

 

[Calais62]

The mileage isn't really an issue in that it had done just over 43000 in 3 years. I have booked it in next week for a check on the DPF. While on the subject,  i am interested in getting the VAG DPF app,  assuming I decide to keep the car. I understand about downloading the app onto my phone but am a little unclear on what exactly plugs into the car.  Presumably some sort of dongle?

[varooom]

40 minutes ago, Calais62 said:

I understand about downloading the app onto my phone but am a little unclear on what exactly plugs into the car.  Presumably some sort of dongle?

@MATT0693or anyone else have link to the dongle?

[SurreyJohn]

3 hours ago, Calais62 said:

The mileage isn't really an issue in that it had done just over 43000 in 3 years. I have booked it in next week for a check on the DPF. While on the subject,  i am interested in getting the VAG DPF app,  assuming I decide to keep the car. I understand about downloading the app onto my phone but am a little unclear on what exactly plugs into the car.  Presumably some sort of dongle?

Do you know mileage split ?

there is big difference between 14-15k per year, compared to 35k then 4k and 4k.   Before you think I am being stupid, there are people who travelled a lot, then changed to working at home from start of covid so car usage fell off a cliff.

 

 

[Calais62]

Just as a PS to my post, I did a return trip to Heathrow yesterday , 200 miles all on motorway mostly at 70-80 mph. An hour after I got home I drove 2 miles into town and an active regen started. Surely after a long motorway journey this should not be happening? On the plus side, I have now made several long journeys in the Karoq and I have to admit it is the best motorway cruiser I have owned.

[Routemaster1461]

Just to satisfy my curiosity, how are you aware that a regeneration is in progress? On one of my previous cars I could tell because the fuel consupmtion went up considerably and performance felt different, and on another I couldn't tell at all. There were owners who fitted diodes near the mirrors to monitor when the mirror heating was on, as the cars switched on electical accessories to increase alternator and engine load.

[Calais62]

Revs at 1000 at idle, stop start deactivated,  and the smell from the exhaust .

[varooom]

5 hours ago, Calais62 said:

Just as a PS to my post, I did a return trip to Heathrow yesterday , 200 miles all on motorway mostly at 70-80 mph. An hour after I got home I drove 2 miles into town and an active regen started. Surely after a long motorway journey this should not be happening? On the plus side, I have now made several long journeys in the Karoq and I have to admit it is the best motorway cruiser I have owned.

It will try to do passive regen, where you burn soot off from the normal exhaust temperatures, that doesn't always clear it, so it will sometimes still do an active regen.

[Sanqhar]

Have you tried using one of the better quality fuels like Shell V-Power.  The different/extra additives in these make for a cleaner combustion.

 

tom