DPF Blocked – Time to think DPF Delete

Categories: DPF Removal

A Sign of DPF Blocked or DPF Blockage.

Emissions Standard.

The abbreviation “DPF” (diesel particulate filter) is a way of life for modern diesel car owners. Since 2007 when emissions standard for new cars came into effect, there has been a lot of hype surrounding the DPF technology. While the claims are that diesel particulate filters do reduce soot emissions, there are quite a lot of disadvantages such as blocked exhausts, poor performance, poor fuel economy, expensive repair bills, diluted engine oil, incomplete regenerations and use of fuel additives that can come with the installation of the DPF system. It might not be all doom and gloom when it comes to your diesel’s DPF, but most owners would rather be without the DPF if given a choice.  Importantly, more often than not, if given the choice, motorists will buy a diesel vehicles that does not have a DPF system fitted.  This is becoming more and more difficult as all manufacturers are being forced to adopt the system as stringent emission laws force them to go this way.   Further, manufacturer’s require the car to be driven “correctly”.  At times, this is not possible as the car is purchased by those that need a “shopping trolley” or a city commute vehicle and juttering along in a “wrong” gear or in stop start traffic means the DPF regeneration process will not occur.  Of course the car salesman is not interested in advising that the car is not suitable and will not describe to the potential buyer that the car may not be suitable to him because of the DPF system fitted.  So the new vehicle owner is completely unaware of what he is getting into with their “economical” driving style which is not “correct” in the eyes of the manufacturer.  The manufacturer does state in the owner’s manual that they requires the vehicle to be driven at highway speeds for around 40 mins and not doing so will be the source of untold problems such as DPF blockages … but who reads an owner’s manual BEFORE they purchase a car?  Certainly not I.


blocked dpf warning light The DPF system consists of a diesel particulate filter, a monitoring system and a maintenance system. The filter in the DPF which is made out of a special porous catalyst material (ceramic, cordierite, metal fibre and silicon carbide) and is responsible for trapping soot emitted from diesel combustion in the engine while letting other exhaust gases to flow through.  The soot collected eventually blocks the DPF.  If driven on the highway often the exhaust can achieve high enough temps so that the soot is burnt off automatically with any active measures taken by the DPF maintenance system.  At a certain threshold, (circa 35%)  the sensors in the DPF trigger a “regeneration” (regen) and diesel particulate matter is burned off .  This is called “post burn injection” or active regen.  Regeneration causes the DPF into clean itself into “as new” condition.  In truth it never is that good and slowly the DPF deteriorates to a point where it fails to reg and a new DPF is needed.   Active regen is commanded by the the factory ECU where by the vehicles diesel injectors inject a small amount of diesel into the exhaust (either via the cylinders and then the exhaust, or on newer DPF systems, directly in front of the DPF itself).  This fuel then burns in the exhaust causing the DPF temperature to raise to a point where the soot in the DPF will burn off (circa 600 deg cel).  Regens can fail at this point if the vehicle is not driven at highway speeds for a long enough period.  If the regeneration fails and the DPF continues to block past circa 45%  a warning light will illuminate on the dash indicating that the DPF systems need to perform a regeneration and that you must drive the vehicle on the highway for at least 20 – 40 mins.  If the vehicle is not driven so that the DPF temps reach 600 degrees Cel the DPF will accumulate more soot.  When it reaches 65% the DPF light will flash and the vehicle will go into limp mode a condition which causes the car to lose 60% of its engine power.  At this point the vehicle needs to go back to the dealer (or a mechanic with the right scan tools) to have a Forced Regen performed.
So, DPF regeneration can occur in two ways: passive and active. In passive regeneration, brisk highway driving causes high exhaust temperatures in the exhaust system which cause the accumulated particulate filter to be burnt off.  As mentioned however, most late model diesel car driven in and around town rarely achieve this temperatures and thus diesel vehicle manufacturers have come up with active regeneration, a process in which the vehicle’s ECU commands post burn injection so the soot (or ash) content in the DPF is reduced.

DPF warning flash light

Possible signs of a DPF blocked include: having the DPF warning light lit (or flashing) on your car’s dashboard and the vehicle struggling to regenerate. This causes an engine code that says that repeated regen have failed.  Drivers who are faced with a DPF blockage have two options in order to regain the diesel vehicle’s horsepower.

  1. To have the whole DPF system replaced or
  2. To use a DPF professional cleaning services.

What’s scary is the fact that a DPF replacement out of warranty will cost you from $3000 – $8000 plus fitting charges.  Aftermarket DPFs are not as good  originals and we see ,000 – 20,000 kms.
Keeping this fact in mind, many owners will go for the other option which is have the DPF totally removed from the system.  This is where Chip Tuning comes into the picture.  Chip Tuning charge less than half to totally eliminate the problem.  We call this DPF Delete.

Apart from the mere ignorance of DPF dashboard warning lights, a DPF blocked can be caused by the driving style the diesel car has been accustomed to. DPF-installed cars were essentially built for the motorway where decent, constant speeds and cruising in a high gear would favour DPF regeneration. For those who buy new diesel powered cars for town-based, stop/start drives such driving styles may result in a DPF blockage. Additionally, a DPF blockage may arise because the DPF system has come to the end of its natural life (which is an estimated at around  80,000 – 120,000 kilometres).   In such a case DPF cleaning won’t do away with the DPF blockage and a DPF replacement should be done.
It is evident that the current Euro 5 legislation is set to be replaced by Euro 6 in 2014, where the permissible levels of emissions will be reduced and since diesel car manufacturers are less likely to adopt additive treatment systems taken the current hassle the systems are displaying in today’s diesel powered vehicles, the correct functioning, or in fact removal of the DPF (called DPF Delete) will become a necessity to deal with problems such as DPF blockages.

Related Article

You can learn more about Air Quality from NSW EPA
Great technical article of the Regen Process is here: DPF_Regen Process

If you have a problem with your car and want to save money, call us to find the right solution now on 02-8090-1881 or click here DPF Removal Service