DPF stands for diesel particulate filter. These filters are used to reduce the number of hazardous particulates that escape the engine exhausts of diesel vehicles. The intention is to keep the air cleaner and safer, especially in confined spaces.
Euro 5 standards
Since 2009, when the “Euro 5′ standard went into force, the exhaust emissions standards for new diesel cars have mandated the installation of DPFs. DPF to the exhaust system. In actuality, the majority of vehicles manufactured prior to 2009 are equipped with also DPF filter.
These steps are considered to be a good thing since DPF (soot) emissions cause severe health issues for humans. DPFs can reduce the amount of diesel soot by 80 percent, but they’re not appropriate for all. Even if your vehicle is not typically urban or stop-start-type, modifications to your driving style could be necessary to ensure that these systems are operating effectively.
What are the diesel particulate filters?
Diesel Particulate Filters (DPF) catch soot particles to avoid them from leaving the exhaust system. As with any filter, they must be emptied regularly to maintain performance. For a DPF this is known as ‘regeneration’. The collected soot is burnt off at high temperatures, to remove only ash.
Regeneration can be passive or active
Passive regeneration
Passive regeneration occurs automatically on the motorway when the exhaust temperature is very high. Since a lot of cars aren’t frequently driven on motorways often, the manufacturers of cars have developed “active” regeneration. In this process, the engine management computer (ECU) is in charge of the process.
Active regeneration
When the filter is filled with soot, it will reach a set limit (about around 45%) then the car’s ECU will begin post combustion fuel injection, which will increase the exhaust temperature and initiate regeneration. If the motor is shut off while the regeneration process is taking place, the regeneration may not be complete, and the warning light comes out to indicate that the filter is partially blocked.
It should be possible to complete a cycle of regeneration and remove the warning light by driving while increasing the temperature as a result.
Signs of active regeneration
During active regeneration, you might notice the following symptoms:
- Cooling fans on
- Increased idle speed
- Deactivation of Stop/Start automatically
- A small increase in the amount of fuel consumed
- A spicy, pungent smell from the exhaust.
- Change in the note for engine
If the regeneration is unsuccessful due to an inadequate driving cycle the extra fuel injected into the cylinders will not burn, and it will be drained through the sump. Therefore, the quality of the oil is deteriorating and the level of oil will increase. The majority of DPF-equipped engines will have an oil quality/viscosity sensor, however, it is imperative to be sure the oil level doesn’t exceed the level that is indicated on the dipstick since diesel engines may run on their own oil if the levels are excessive, often to the point of destruction.
If you disregard the diesel particulate filter warning light and keep driving in a fairly slow, stop/start pattern, soot will continue to build up until around 75% when you will likely see more dashboard warning lights go on. At this point, driving at a steady speed won’t be enough to completely clear the filter, and you’ll be required to bring the vehicle to a dealership to have “forced” regeneration.
Forced regeneration
The forceful regeneration process is required when “active” regeneration criteria have not been met, and soot levels in the DPF have increased to about 70 percent. If left in place, the loading of soot will continue. At this point, an instrument for diagnostics must be employed to trigger regeneration. At around 85% soot loading, regeneration can no longer be achieved on the vehicle. You will need to get rid of any DPF to be replaced or cleaned.