Honda's views on their DPF's

[OldKel]

Hi did start a DPF thread on the Accord forum but guessing it probably applies to more than one vehicle in their range.

But as I did not get a reply tried to hunt around the net but came up blank so put a complaint into Honda.

Did get too escalations but not much joy help wise but thought I would share their reply and my take on it.

Probably do this in two parts. first up an overview then tomorrow will try and clarify how the first stage DPF regen works as that really threw me.

forgive me if I mess up with any images.

Honda’s position on their diesel cars is:-

“Please be advised that the Diesel Particulate Filter is an exhaust component which is heavily affected by wear and tear, driving style, external influences, etc. Driving in heavy traffic – regular short commute, less than 20 miles each way; annual mileage less than 10,000 miles a year; driving at slower speeds for prolonged periods – average speed under 30 mph are a few of the reasons that may lead to a replacement of the DPF filter being required.”

I think this means!

Basically if you are doing less than 10,000 miles a year, and your journey is over 20 miles and can be completed at average speeds above 30mph. expect to have issues with your DPF filter.

 

To put this in context

Government figures for 2021

https://www.gov.uk/government/statistics/travel-time-measures-for-the-strategic-road-network-and-local-a-roads-april-2020-to-march-2021

On the Strategic Road Network (SRN) for the year ending March 2021, the average delay is estimated to be 5.9 seconds per vehicle per mile compared to speed limits travel times, a 36.6% decrease compared to the year ending March 2020.

The average speed is estimated to be 62.6mph, 6.3% up on the year ending March 2020.

On local ‘A’ roads for the year ending March 2021, the average delay is estimated to be 32.0 seconds per vehicle per mile compared to free flow travel times. This is a decrease of 26.8% on March 2020.

The average speed is estimated to be 27.8 mph. This is an increase of 9.9% relative to the year ending March 2020.

Could not find goverment figures but car insurances appear to work on for 2021

 

https://www.nimblefins.co.uk/cheap-car-insurance/average-car-mileage-uk

 

Average Car Mileage UK

In 2020, the average car in the UK drove 6,800 miles—down 8% from 2019 and down 26% from 9,200 miles in 2002. British motorists drive less now, primarily driven by a drop in business driving and private driving. Clearly the drop from 2019 to 2020 reflects the impact of the pandemic lockdown.

Commuting mileage had held steady at 2,700 miles a year on average per car from 2002 to 2019, but dropped to 2,400 miles a year in 2020. From 2002 to 2020, business mileage plummeted 85% from 1,300 to 200 miles per year. Private mileage only dropped 7% from 2019 to 2020. This means commuting and business miles were impacted the most by the pandemic lockdown; private miles less so.

Change in UK Driving Habits	Business Miles	Commuting Miles	Other Private Miles	Average Total Miles
2002	1,300	2,700	5,100	9,200
2019	400	2,700	4,400	7,400
2020	200	2,400	4,100	6,800

The average car journey for these cars is 8.4 miles long.

UK motorists are driving less, especially for business

During a time when cars are being driven less and less, it's interesting to note that the number of cars licensed in the UK has continued to rise steadily—so while the mileage per car has dropped, you could argue that as a country we are driving more.

Average Mileage per Day, Week, Month and Year

How much do we drive per day, week or month? On a daily basis, cars in the UK drive an average of 20 miles a day, 142 miles a week, 617 miles a month and 7,400 miles a year.

Average Car Mileage per Day, Week, Month and Year	2019	2020
Per Day	20	19
Per Week	142	131
Per Month	617	567
Average Total Miles per car	7,600	6,800

 

So from the graph and the tables on average it looks like most fall short of what we should be doing

 

I am afraid that it does mean we are on our own, for being so short sighted.

I wonder if you could assume that the all new HR-V Hybrid will be similarly slighted, if and when any car that contains an engine is prevented from going into cities, and Honda will probably tell the hybrid owners they should have bought the full electric version. After all I was told I should have bought the non-existent petrol type S version of my car.

 

Hope it clears some stuff up though

 

Regards

Kel

[OldKel]

 Second bit this time about the DPF indicator itself

 

A diesel engine without compromise

 

Honda’s position on how the stage 1 DPF purge works on their diesel cars is officially: -

Well sort of official I did ask for clarity and received the following reply

“I have had the opportunity to thoroughly investigate your concerns further and have now spoken with Holdcroft Honda, Cobridge at great length to understand this matter. The service team there have confirmed that having had the opportunity to inspect your product they have been unable to diagnose or find a manufacturing defect with the DPF warning light and have advised you that whether the light will come on depends on the driving style.”

And this is how it was explained to me at said dealer

The car monitors the journey you are taking and if you have been driving for the correct amount of time at a suitable consistent speed, along with such things as temperature engine and probably outside temperature etc. Plus it thinks the DPF needs a purge. Then the indicator lights up to tell you it’s about to enter into DPF cleaning mode.

It is generally accepted that a DPF purge needs to happen in one operation so as far as I am aware you cannot do three quarters, then go out and do the last quarter at another opportunity, so in the unfortunate event that you was approaching your journeys end or some body makes you slow down and drop out of the purging process or similar, the entire process will need to be done again, however you are at least in a position where you are now aware your DPF filter needs purging. So I reckon you need as soon as possible to retrace your journey and fingers crossed your Hondas computer will try again (yes that one that thinks British summer time started at Christmas!).

I would recommend doing the second journey at a time when the motorway is quieter, I believe that motorways are generally where the car is happy to do a DPF purge as it is most likely to satisfy Hondas recommended use ie

“ Please be advised that the Diesel Particulate Filter is an exhaust component which is heavily affected by wear and tear, driving style, external influences, etc. Driving in heavy traffic – regular short commute, less than 20 miles each way; annual mileage less than 10,000 miles a year; driving at slower speeds for prolonged periods – average speed under 30 mph are a few of the reasons that may lead to a replacement of the DPF filter being required.”

If you are successful you could probably have a celebratory Swedish Meatball at an Ikea that you don’t normally get as far as.

Unfortunatley you will not be able to follow some motoring organisations advice ie the A.A. advise

https://www.theaa.com/driving-advice/fuels-environment/diesel-particulate-filters

Don’t ignore a warning light

If you get a warning light showing that the filter’s blocked, it should be possible to complete an active regeneration cycle and clear the warning light by driving for 10 minutes or so at speeds over 40mph. (Similar to my handbooks 15 minutes and 37mph)

If you ignore a DPF warning light and keep driving in a relatively slow, stop/start pattern, soot will build up in the filter until your car goes into ‘restricted performance mode’ to prevent damage.

If you let it get this bad:

• Driving at speed alone won’t be enough.
• You’ll have to get a dealer to do a manual or ‘forced’ filter regeneration.
• In extreme cases they may have to replace the filter which can cost at least £1000 plus labour.

In most cases there’s only a short time between the DPF being partially blocked and it getting so blocked it needs a manual regeneration.

 

You cannot do this because it appears the following function:- 

As been apparently removed from your car’s computer.

However I am open to hear from anyone who may have had the light come on in the way the handbook describes, and how they went on, as the main reason for posting this is because there is very little out there in the way of information. Even if we get some feedback of experiences with the light coming on we may be able get an idea of what we can do to trigger a purge without resorting to bothering the dealers.

Hopefully this at least clarifies what’s happening with your DPF light.

 

[Trevor]

Thank you for posting this information which will certainly shine some light on the subject of DPF's

Post is now pinned and featured in this forum section

[OldKel]

Hi Trevor

 

Thanks for pinning, was hoping it was not too controversial.

 

Regards

Kel