A Complete Guide To Your Diesel Particulate Filter
Diesel cars are still an attractive choice for drivers who travel long distances as they often have a much higher mpg figure than the petrol equivalent, so are seen as more cost effective. However, all diesel vehicles are now fitted with a diesel particulate filter to reduce emissions, while this is a positive addition for the environment many motorists worry about extra costs they may incur should the filter become clogged or need to be replaced. Here is Rivervale's guide to your diesel particulate filter ...
For years as consumers we were encouraged to buy diesel vehicles as they produced less carbon dioxide than petrol. What was overlooked were all the other nasties released from the exhaust pipe known as particulate matter and the negative affect this can have on a person’s health. In response to this concern diesel particulate filters were fitted to every diesel vehicle made from 2009 to control which substances are released in the cars fumes.
What is Diesel Particulate Matter?
In a diesel engine, diesel fuel is injected into the engine cylinder where it mixes with air and combustion occurs. This reaction creates the power to move the vehicle, but also produced some waste products. The waste products include pollutants such as sulphur dioxide, nitrogen oxide and particulate matter, which are all expelled from the engine as exhaust fumes. Diesel Particulate Matter is the name given to a groups of pollutants which can be solids or liquids and are different sizes. Smaller diesel particulate matter is of particular concern as its size means it bypasses the body's natural filtering processes, such as nose hairs, and can enter deep into the lungs. Diesel Particulate Matter has been associated with many serious health conditions such as heart and lung damage as well as certain types of cancer. Study into the implications of inhaling diesel particulate matter first began in the 1970's, but research continues to uncover the full effects of this pollutant.
What does my Diesel Particulate Filter do?
Your diesel particulate filter will reduce the amount of pollutant including particulate matter released. It does this by passing the vehicle’s fumes through a filter which traps solid and liquid particles and then burns them off at a high temperature to leave behind only a small amount of ash.
The European Union create air quality standards which all manufacturers must ensure their vehicles emissions meet. The Euro 5 standard effectively made diesel particulate filters mandatory in 2009. The Euro 6 standard applied to all newly registered cars from September 2015 and was very challenging for diesel cars as emission limits for diesel cars were brought more in line with those for petrol cars. For example, under the Euro 5 standard a diesel vehicle could emit up to 180mg/km of NOx, this was reduced all the way down to 80mg/km by the Euro 6 standard. These changes mean diesel cars are cleaner than ever, and can be seen to be as kind to the environment as their petrol equivalents.
Diesel particulate filters have proved a major benefit to the environment and to our health by reducing air pollution.
Does my diesel particulate filter require any care?
Your filter will need to be cleared of any trapped matter regularly in a process called ‘regeneration’. There are 2 types of regeneration, the first is passive regeneration and the second type is active regeneration.
#1 Passive Regeneration
Passive regeneration is an automatic process which needs certain conditions to occur;
- The vehicle has been driven for around 10 minutes at 40mph or above.
The vehicle needs a long journey at a higher speed to generate enough heat to burn soot trapped in the filter and turn it into ash.
However, there are many drivers who do not meet these conditions, who take frequent short journeys that will not allow passive regeneration to take place. For this reason, most manufacturers have now built in a sensor which detects when the diesel particulate filter is becoming blocked. When this happens, active regeneration will be triggered.
#2 Active Regeneration
If the engine management systems detects the diesel particulate filter is becoming blocked it will start active regeneration. In this process extra fuel is injected into the engine cylinder to raise the temperature enough to trigger regeneration. During the regeneration process you may notice some differences with your vehicle such as;
- Automatic stop/start no longer works
- Engine sound is different
- An increase in fuel consumption
- The engine idle speed is faster
- The cooling fans are running
- There is an acrid smell from the exhaust
These changes in your vehicle will all return to normal once the regeneration process is complete, which can take up to 10 minutes.
What should I do if my Diesel Particulate Warning Light Comes on?
If your filter becomes too saturated a warning light will appear on the dashboard. It is important not to ignore this. If your filter is not regenerated it will reduce the performance of your vehicle and damage the filter.
If your diesel particulate warning light comes on the AA advises the following ...
Drive at 40mph or more for at least 10 minutes
This may be enough to complete regeneration and your warning light may turn off.
A blockage may occur if the regeneration process has been continually interrupted. So, in most cases if your vehicle is driven in the correct conditions for regeneration, at 50mph or more for at least 20 minutes, the filter should clear and the light turn off.
In cases where the light still remains on, the vehicle will need to be taken to a garage to be cleared.
Can I Remove my Diesel Particulate Filter?
When diesel particulate filters were first introduced some drivers had them removed as they feared problems. You should never ever remove your diesel particulate filter – From February 2014 all vehicles who have a missing diesel particulate filter when one would have originally been present will fail the MOT. Removing a diesel particulate filter will also invalidate insurance as the vehicle is not legal for road use. The cost of putting a filter back again could be in excess of £1,000.
If you regularly make short, low speed journeys you should talk to one of our Account Managers at Rivervale to discuss whether a diesel vehicle is the right choice for you.
Eventually ash will build up in the diesel particulate filter and will need to be cleaned/replaced at a garage. However, if a car is looked after correctly this shouldn't occur until after 100,000 miles.
Does a diesel particulate filter put you off buying a diesel vehicle?
The comments above do not necessarily reflect Rivervale's views unless clearly stated.
26 July 2017
Written by Natalie Faughy