Diesel Particulate Filter (DPF): What You Need to Know

Tim Miller

People who own diesel cars have diesel particulate filters. However, most people lack the slightest clue how to maintain the particulate diesel filter in their vehicle, resulting in the filters clogging with soot.

For two decades now, we have fitted diesel particulate filters in diesel fuel vehicles. Nonetheless, if tampered with or lacks superior maintenance, your car ends up with severe consequences.

Diesel particulate filter, as the name filter suggests, trap or ‘filter’ particles. The particles are diesel exhausts soot particles, and therefore, you have to empty occasionally to maintain good performance in your vehicle.

The DPF (Diesel Particulate Filter) requires regular cleaning by a process referred to as regeneration. The process is either active, forced regeneration, or passive.

This article will explain precisely all you need to know about the diesel particulate filter and ways of maintaining it.
In this article, you’ll learn all about the diesel particulate filter (DPF)

What is a diesel particulate filter (DPF)?

Diesel particulate filter is a trap or rather a filter just like the name filter, that captures and stores exhaust soot or soot traps from your vehicle to reduce emissions from diesel vehicles.

However, because the soot trapped is infinite capacity, you need to empty it periodically to avoid blockage and regenerate the diesel particulate filter (DPF).

The regeneration process burns off the trapped soot, which is deposited in the vehicle’s filter, reducing harmful exhaust emissions to the environment. This process also prevents the tell-tale black smoke release, which we used to see many years ago from diesel cars, especially when the vehicle was accelerating.

The accumulated soot is burnt off around 600degrees Celsius at high temperatures, leaving only ash residue that effectively regenerates or renews the filter ready filter more particles. From the vehicle.

In simple terms, diesel car owners refer to the regeneration process as taking soot pollution from the car’s engine and storing it ready to get rid of it. That is the reason why you have to clear the soot occasionally.

Diesel emission is harmful to our health and the environment at large. The good news came in 2009 when the Euro 5 Exhaust emission legislation was introduced to help lower vehicles’ CO2 emissions and effectively made diesel particulate filters a must have for any diesel car.

Since then, the diesel particulate filters are fitted in all diesel cars, or one in every two vehicles a year are diesel-powered.

After all, the measures put in place to have the safety filter. As we can call it, it has shown incredible results. There is no emission of harmful back smoke.

What causes a diesel particulate filter (DPF) blockage?

Every vehicle and car engine combination has different reasons as to why the filter can block. They can be caused by reasons like the rate at which the car is releasing the soot, oil quality, driving style, fuel quality, and the location of the particulate filter (DPF).

All the above reasons, one or another, cause diesel vehicle filters to block and fail to regenerate fully.

Generally, most problems arise with vehicles doing town rounds since the regeneration process is not happening as it should.

In this case, a diesel vehicle driver should be on the lookout for a message or an illuminating light that shows the diesel particulate filter (DPF) is not functioned as per the requirements.

The message is a warning that if you continue to drive in the same manner, the soot accumulates, and the vehicle goes into a limp mode where even driving at speed is restricted.

This buildup of the soot where the vehicle accelerating speed has been filtered requires the mechanic to carry out a forced regeneration on the vehicle’s filter.

To know about the Diesel Particulate Filter, you should know what causes DPF blockage
These are some common causes of a DPF blockage

The breakdown of what causes particulate filter blockage:

  • Frequent small journeys where the diesel vehicle’s engine fails to get hot.
  • Wrong and low-quality engine oil.
  • When the fuel level is low, generally, when the oil is less than a quarter, active regeneration fails to take place.
  • Suppose your car uses Eolys additives. Low levels of oil in the tank prevent regeneration.
  • Problem with vehicle fuel system resulting in excessive soot.

How do you maintain your vehicle’s diesel particulate filter (DPF)?

DPF is where the filter will reach a predetermined unit, mostly at 45%, and raises the exhausts’ temperature burning off the trapped and stored soot.

When extra fuel is automatically injected, there is an active regeneration as part of the car’s ECU. This is where the filter will reach a predetermined unit, mostly at 45%, and raises the exhausts’ temperature burning off the trapped and stored soot.

Problems arise when the vehicle’s journey is short as the process of regeneration fails to go a full cycle.

If this happens where the soot blocks the filter, look out for a warning light on the dashboard. This sign now means that it is time to visit a mechanic who carries the forced regeneration.

However, if you continue driving for around ten minutes at a speed higher than 50mph, the warning light clears, which means the filter is also minimizing the blockage.

Symptoms to look out for and know if the vehicle has active regeneration:

  • Engine note changes.
  • Fuel consumption a slight increase.
  • Idle speed increases.
  • Acidic, the hot smell coming from the exhaust.
  • The cooling fans are running.
  • Automatic deactivation of the start and stop.

Passive regeneration

Passive regeneration happens when the vehicle runs at speed on long motorway journeys, which enables the exhaust temperatures to increase to high levels and completely burn off the buildup soot at the filter.

We recommend diesel car owners to regularly give their vehicles a considerable 30-50 minutes of a sustained quality speed on the motorway to help and clear the filter.

However, most drivers hardly take this kind of driving. That is why manufacturers designed an alternative type of regeneration.

What do I do if both active and passive regeneration fails to work?

If your vehicle does not have passive or active regeneration, then a warning light comes up to show that the soot has wholly blocked the filter.

This is the time to have your vehicle checked out. If the warning light stays on, it turns red, and additional DPF lights pop up. It is advisable not to ignore these signs as they may result in the vehicle getting expensive damages.

This is where forced regeneration now comes to play.

Forced regeneration is expensive as you have to carry the process in the workshop with a mechanic’s help.

Forced regeneration is the process of removing excess or build up soot, in this case, in the garage, to make the vehicle regenerate again by itself automatically.

Failure to have forced regeneration happens. The vehicle develops limp mode as the filter is clogged and does not emit smoke. Some vehicle models will work well after being subjected to a moderate speed of 50 mph.

Do I require diesel particulate filters to pass through the MOT?

Yes. Reason? In any case, if you remove the filter, the vehicle fails its MOT. Since 2004, diesel particulate filters have always been part and parcel of the MOT tests.

Removing the diesel particulate filter causes the warning lights to show. This is a simple term, and it is an MOT point of failure. The warning lights on the dashboard should always remain during the vehicle test.

The Bottom Line

Generally, diesel produces a lot of soot, which is particulate matter that can cause health problems like respiratory problems and cardiovascular diseases.

Since 2009, modern diesel vehicles are fitted with diesel particulate filters in their exhaust to stop the soot from passing through to the atmosphere and causing environmental problems.

This aim cut over 80% of the particle emissions from diesel vehicles.

Important notes

To avoid all the issues that result from the clogged exhaust, here are five points to consider you are trouble free.

  • Drive faster
  • Always have the EGR valve checked frequently.
  • Use the right engine oil.
  • Drive for long-distance and keep out of cities and towns
  • Lastly, buy the right engine vehicle.
Okay, now you have all the information you need to know. Keep the diesel particulate filter on your vehicle in good shape.

Bonus: Best Heavy Duty Truck Scan Tools Review 2021

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