Emissions manufacturer debunks DPF myths and warns against illegal removals

Diesel particulate filter removal could result in hefty fines for motorists

Emissions manufacturer debunks DPF myths and warns against illegal removals
The DPF plays an important role in processing the harmful soot particles that are produced by the combustion process. Image: Bigstock.

Since its introduction in 2001, the Diesel Particulate Filter (DPF) has been the subject of controversy – Doug Bentley, head of product development at Klarius Products Ltd explores the issues surrounding the confusion on DPFs.

DPFs are a filter device, constructed of a metal casing containing an internal ceramic monolith.

The regeneration cycle is a controlled burn-off that happens inside the DPF where soot is burnt through to form less harmful gas and fine ash which remains in the DPF.

Regeneration tends to occur when the DPF reaches a high temperature for a prolonged period, such as motorway driving.

The MOT test includes a DPF check for diesel vehicles if the component was fitted from new – so why are some motorists and garages illegally removing DPFs from vehicles?

Doug Bentley said: “Many owners of diesel vehicles who only make short journeys will notice that the DPF fills quickly and does not regenerate.

“The exhaust system cannot reach a suitable temperature on these journeys, so the soot is given no opportunity to reduce, and so clogs the monolith.

“Some motorists will assume that it’s the component that is faulty and may opt to remove the DPF entirely as clogging continually reoccurs.

DPF removal ‘black market’

“This is illegal and will actually start to damage the car as well as adding highly carcinogenic pollutants into the atmosphere.

“The situation can be avoided by simply taking the vehicle on a long journey once a month, providing an opportunity for the DPF to burn off the excess soot.”

Doug believes this knowledge is not passed on to diesel owners, which has helped to create what he calls a “black market” specialising in DPF removals.

It is now a legal requirement for a DPF to be present on a road going vehicle if it was fitted from new.

The absence of a DPF on an applicable diesel vehicle will result in an automatic MOT test failure.

Doug warns motorists that removal can lead to costly repairs for the owner to make the vehicle roadworthy again.

Service item

“DPFs used correctly can still be a service item; during normal use for some vehicles it will eventually become full of ash.

“The performance of the vehicle will also noticeably deteriorate as the exhaust gas stream is hindered.

“This will usually result in a full DPF replacement.

“When and if this happens depends on the rate at which a DPF becomes blocked.

“Small cars with ‘dirty’ engines will last 60-80,000 miles before a replacement is required.

“Vehicles mostly used on the motorway may last 150,000 miles plus, or, the lifetime of the vehicle.”

Poor quality DPF replacements

Klarius type-approves aftermarket DPFs, an EU standard for emissions and product quality, which means Klarius DPFs are comparable to the original in terms of performance.

Doug said: “Klarius has seen independent test results that clearly show some suppliers are not so stringent.

“The main area of compromise is the size of the internal ceramic monolith, which in some inferior replacements, can be half the size it should be in order to match the OE equivalent.

“This of course means the DPF clogs much quicker when installed, causing an increased likelihood of failure and providing another excuse for complete removal.

“Some DPFs are also designed with a precious metal coating on the ceramic monolith, which acts as a catalytic converter for further reducing emissions, this is often very light, or absent on cheap replacements.”

Click ‘more details’ below for further information about Klarius.

Do you offer DPF removal services or know a workshop that does? Leave your comments and experiences in the comments below.

11 Comments

  1. As an automotive technician and owner of a car fitted with DOG and a resident on the Isle of Man I find it impossible to do enough miles to regenerate the DPF. The Island is 37 miles long and 15 miles wide so what is the industry’s suggestion in this case? Jersey and Guernsey will be having similar issues.

    Reply
    • In answer to your question Graham. The most modern Euro 5 & 6 engines will perform what’s called “continuous regeneration” this is to allow regeneration at low speeds and reduced engine temps, I have proved this by scoping injectors and post injection occurs at low engine load (even stationary in some cases) thus allowing “Continuous Regeneration”

      Reply
  2. Hi Graham as you know, a forced regen can be done by the franchised garage in situations where the DPF is clogged and a vehicle regen hasn’t been possible. Mostly this is an automated process with little technician intervention and so shouldn’t cost much to have done (Although it will depend where you go). Still less expensive than a replacement DPF.

    I’m interested, how did you fit a DOG to your car?!

    Reply
  3. Car must run a bit Ruff! ..sorry could not help it !

    Reply
  4. Why do you need a diesel on Isle of Man?
    Just buy a petrol & enjoy hassle free motoring.

    Reply
    • Graham – no mot in guernsey / jersey so removal is an option.
      Using a product like TerraClean’s DPF cleaner will desolve the soot and restore the effecency of the DPF I believe there is an agent there for TerraClean give them
      a bell …

      Reply
    • Exactly. Why would you buy a diesel car on an island. Better advice required. I have been telling people that do small milages to keep clear of diesels for years.

      Reply
  5. Never been a diesel fan . It really is nonsense – stop the rubbish in the exhaust escaping day to day , then do more miles than you normally would to burn it out into the air , probably in a country area (to do the miles ) so the carbon (as gasses) and other nasties still go into the air.

    Reply
  6. Further more I note a DPF cleaning gun is available (advert in another Garage Wire report)Quoting it dissolves the carbon ! WE all know (don’t we ?) that you cant dissolve carbon – mobilise it maybe , but what happens to it then ? Without taking the DPF off , it will be blasted into the atmosphere …..again

    Reply
  7. DPF removal takes place because the cost to replace is too high. There should be a zero % profit enforced on all emission based units like DPF. CATs. EGR ect. I’ve also still failed to find proof these emission system actually reduce pollution long term.

    Reply
  8. Doug Bentley is quite correct when he says that the soot will turn to ash which cannot be burnt off. It cannot be removed using various on vehicle chemical treatments either. However a DPF which is full of ash does not require replacement. Certain cleaning methods such as The Flash Cleaner machine will remove the ash from the DPF by back flushing the unit and basically restoring it to as new condition. This would involve removing the DPF from the vehicle to carry out the cleaning operation. The results are certifiable by before and after back pressure and flow readings which are printed by the machine. There is so much disinformation on this subject which gives the DPF such bad press. Properly serviced and looked after including rectification of faults which cause the DPF to block in the first instance, the DPF is a very valuable product in terms of protecting the environment.

    Reply

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