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Diesel Particulate Filter (DPF)


What is a DPF?

A Diesel Particulate Filter (or DPF for short) is a filter found in the downpipe section of the exhaust and is specifically designed to reduce the amount of Diesel Particulate Matter (Soot/Ash) passing through. The objective of this filter is to create cleaner / more eco friendly exhaust gases being release into the atmosphere. 

The purpose of this filter is to reduce pollutants resulting from combustion from being released to the atmosphere...

A diesel particulate filter will gradually become restricted and become more clogged up as a normal part of it's service life, a process called regeneration is designed to occasionally 'clear out' the particulate filter. Unfortunately this needs specific driving conditions and when these are not met, the degree to which the filter is blocked can surpass the engine managements ability to regenerate the filter - leading to problems with power loss (see detailed list below) and even in the absolute worst case, risk to the car due to overheating of the filter.

The images on the right show different examples of the a DPF, as you can imagine with the first image this is very restrictive and easy to block causing the fault codes and running problems on the car. 


A blocked DPF can cause many problems including loss of power, economy and throttle response. With more extreme cases, filters that are extremely blocked filters can cause the engine not to start at all.

Potential Causes

Generally speaking a blocked DPF is usually caused by another underlying issue. It is worth undertaking further diagnostics to find the route cause of the blockage.

Things what could lead to a blocked DPF:

  • Short Journeys - Vehicles doing a a lot of 'town driving' are a more likely to block up due to the DPF not getting up to temperature. For the DPF regeneration process to work effectively and burn off the carbon deposits the engine needs to frequently get up to temperature.

  • Faulty / Failed Sensors - DPF's have several sensors that are installed before and after the filter. These sensors are fitted to monitor the Pre and Post temperature and pressure of the filter. If one or more of these sensors fail the regeneration process may not be carried out effectively.

  • Faulty / Failed EGR Valve - The EGR Valve is designed to recirculate exhaust gases back into the engine before they pass through the DPF. If the EGR is not working effectively or blocked the amount of exhaust gases passing through the DPF will be increased potentially speeding up the DPF blocking.

  • Faulty / Failed Swirl Flaps - Similar to the EGR Valve the swirl flaps are fitted to help with the emissions control on the vehicle, if theses are not working effectively it can potentially speeding up the DPF blocking

  • Failed Regeneration - For the DPF to regenerate there are certain conditions to be met. If these prerequisites are not met the DPF will fail to regenerate. See here for more info - http://wiki.ross-tech.com/DPF

Symptoms and Fault Codes

There are multiple faults codes and symptoms that can point towards a faulty / blocked DPF.


  • Loss of power
  • Lower fuel consumption 
  • Reduced throttle response
  • Harder / Fails to Start
  • Limp Mode

Warning Lights:

  • DPF Light (yellow symbol in the top photo)
  • Coil and Engine Management lights

Fault Codes:

  • 009263 - Diesel Particulate Filter (Bank 1): Restricted/Clogged
  • 16855  P0471  001137 - Exhaust Pressure Sensor 1 (G450): Implausible Signal
  • 18434  P2002  008194 - Particle Filter Bank 1: Malfunction



There are 4 main solutions when you experience a blocked DPF. It is also worth diagnosing the vehicle as a lot the time a blocked DPF is caused by another issue (Faulty Sensor,  

1. Forced Regeneration
The first solution is to try a forced regeneration. This is for cars that have only just started to show symptoms that the DPF is blocking. If this fails to work the DPF may be too far gone for this process.


  • If the forced regeneration process is successful this is the cheapest way to cure a blocked DPF.


  • A forced regeneration cannot always be preformed depending on how blocked up the DPF is. 

2. Replace
The second solution would be to replace the DPF. Generally from the dealers these are quite expensive some costing upwards of £1500 + VAT. Aftermarket DPF are also available at a fraction of the cost but are usually of lesser quality.



3. Clean
The third solution would be to clean the DPF. To do this properly the DPF would need to be removed. Some companies will offer a cleaning service with the DPF still fitted on the vehicle but this is not as effective. 



4. Remove
The forth solution is to remove the DPF all together eliminating the problem with no risk of the same problems occurring in the future. 
In the UK this is now illegal. Vehicles with the DPF removed will fail an MOT.
(When purchasing our parts it is the customers responsibility to ensure they comply with rules and laws relating to their home country)



Stainless DPF Downpipes

Here at Darkside Developments we offer a full DPF hardware and software removal service for all VW, Audi, Seat & Skoda TDi engines. For certain makes and models we can offer a complete Stainless Steel Downpipe which completely removes the DPF section of the exhaust and fits directly in place of the standard downpipe. For the models we can’t offer these downpipes to off the shelf we have all the facilities in our workshop to custom make them on the car.

See here for available Stainless Steel DPF Downpipes: https://www.darksidedevelopments.co.uk/de-cats-dpf-deletes/ 

Standard DPF Filter Removal 

Another option we have is to cut out the filter itself from the DPF housing, still removing the problem but visually leaving the DPF Housing in its original place for visual inspections. This method can also be carried out at home if you have the correct tools and equipment available.  

See here for a DIY DPF Removal Guide: http://www.vwwatercooled.com.au/forums/f28/dpf-removal-guide-71644.html

Once removed you can then send us your ECU to remove the software faults stored on the cars memory. Follow the steps in this listing: https://www.darksidedevelopments.co.uk/products/ecu-dpf-software-removal-service.html 

Software Removal

When deleting the DPF in the software we remove all of sensors other than the Pre-Turbo EGT Sensor and Lambda Sensor.
Other companies tend to keep all of the sensors in place and although the some of these sensors are not in use they can cause issues further down the line. If any of these sensors fail it can cause the car to go into limp mode or constantly turn on the fans.

Regeneration (For Cars Showing Early Signs of Blockage)

For cars that have only just started to show symptoms that the DPF is blocking you may be able to get away with a regeneration. If this fails to work the DPF may be too far gone for this process.

See here for details on the regeneration process - http://wiki.ross-tech.com/DPF


EGR Removal

After deleting the DPF we are also able to delete the EGR Valve, this valve is used to lower the emitions of the car but are often prone for failing. The valve works by recirculating some of the exhaust gases back into the engine through the air intake system, reducing the amount of emitions that exit the car.

The problem lies with the exhaust fumes that contain carbon deposits, these fumes are constantly being recirculated through the engine which over time will cause a build-up of the carbon deposits in the intake manifold and other in other parts including the EGR valve. This build up in the valve is often what causes them to fail. 

There are two ways of removing the EGR System from the vehicle. The first way is by using one of our EGR Delete Race Pipe Kits, these can be found on our website here: https://www.darksidedevelopments.co.uk/egr-valves-and-parts/

Some cars may have a different EGR Valves or ones that are built into the inlet manifold. If this is the case we can still remove the EGR using blanking plates.

Once the valve is either removed or blanked off the vehicles ECU will no longer get a signal from the EGR Valve causing the emmisions workshop light to appear on the dash board. We can remove this by reprogramming the EGR software on the ECU.

Benifits of removing the EGR Valve

  • Lowered Engine Temps
  • Improved Throttle Response
  • Improved Economy
  • Reduces Oil Contamination
  • Reduces Carbon Deposits in the engine

The EGR Valve CANNOT be removed on vehicles that still have the DPF Filter present, doing so would soon block the DPF.


Post your ECU

We can also remove the DPF software from the ECU without the car in our workshop. If you want to carry out the DPF removal yourself from home or a garage but don't have the equipment to remove the software, you can now send us your ECU and we will remove the software and send you the ECU back in the post, ready to just plug and play go.

See here for our ECU DPF Software Removal Service: https://www.darksidedevelopments.co.uk/products/ecu-dpf-software-removal-service.html

DPF Workshop Services

If you are not confident in doing to work yourself, we can do everything in our workshop.



Will removing my DPF cause any problems?

No, in fact having a DPF will cause more problems than removing it altogether. Once the DPF is removed there is no need to worry about regenerations, power loss or expensive bills from the dealers.

How long does it take?

Usually if we have the car in the workshop for 8am we will be able to do a full DPF removal (hardware and software) in the same day. If we are also remapping the car this can sometimes spill over into a second day as all our maps are custom and can require some fine tweaking. The time can also be dependant on the make and model of the car.

Does it affect fuel economy?

A blocked DPF will use more fuel than usual as it is making the engine work a lot harder, removing the DPF will help the exhaust gases flow freely which in most cases will see an increase in MPG.

Will it still pass an MOT or other Emission tests? 
It is the customers responsibility to ensure they comply with rules and laws relating to their home country. Darkside Developments accepts no responsibility for the use of this part on the public highway where removal of emissions controls is prohibited.