Your Guide to Maintaining Diesel Particulate Filters

Diesel particulate filters (DPFs) are vital to reducing emissions. They trap particulate matter that would otherwise exit with the exhaust. This matter is trapped and then eventually burned, transforming potential pollutants into ash, carbon dioxide, and water. However, over time, diesel particulate filters suffer from particulate matter buildup, and do require maintenance in order to continue doing their job.

The Results of Incorrect, Insufficient, or No Maintenance

To help illustrate just why it is so important that particulate filters are maintained properly, let’s take a look at toms of the issues that can occur when they are not correctly maintained. A host of different symptoms can occur, all of which are the result of increased back pressure and restricted exhaust flow within the system.

The most common result here is the need to replace the filter completely. However, in between failure to maintain and replacement of the filter, vehicles will lose power, and engines will deteriorate and suffer damage. In a worst-case scenario, it could result in the destruction of the entire engine (meltdown). Ultimately, you spend much less time and money by properly maintaining particulate filters, rather than dealing with the ramifications of a failure to maintain them.


There are two types of regeneration when it comes to DPF systems – passive and active. Passive regeneration occurs with the filter still in the system. The exhaust gets hot enough that matter is burned without having to remove the filter. Active regeneration requires an outside source of heat, such as electricity applied to the filter. This may be done on the vehicle and be initiated by the driver, or it could occur in a cleaning system after the filter has been removed.

Understanding Your DPF Monitoring System

Each vehicle equipped with a diesel particulate filter should also have a filter monitor, or DPF monitoring system. While each one differs somewhat from manufacturer to manufacturer, they tend to be relatively similar in the way they operate, at least in terms of indicator lights used to convey information to drivers and maintenance technicians.

A green light indicates that the filter is fine and no cleaning is necessary. If the green light is flashing, it means that there is a regeneration in progress. Note that frequent regenerations can indicate a problem with the engine that may be causing excess particulate matter to be dumped into the exhaust stream. This should be investigated and rectified.

An orange light indicates that the filter needs to be serviced. Note that if the light is flashing orange, rather than solid orange, it indicates that a regeneration is necessary, but has not occurred. Finally, a flashing red light means that the filter must be regenerated immediately. Failure to do so could void your warranty.

All indicator lights convey important information. Vehicle operators should be trained to pay attention to these lights, as it could result in serious damage to the vehicle.

How to Maintain Your Diesel Particulate Filter

Your truck’s DPF is not a fit and forget sort of item. It requires maintenance, and that maintenance should be performed regularly. As the filter accumulates particulate matter, it goes through regeneration cycles (both active and passive). These generate CO2 and water, but also ash that cannot be burned. The ash builds up in the filter, clogging it and increasing back pressure while restricting the flow of exhaust.

To avoid that problem, you need to ensure that you remove the DPF periodically and clean out the ash. Each DPF has different maintenance requirements as dictated by the manufacturer. Make sure to read through the literature that was supplied with the filter to ensure that you are using the right products and taking the right steps.

Despite the fact that different cleaning procedures may be necessary with various filter types out there, there are some similarities. For instance, a DPF cleaning machine should be used to ensure that ash is not only removed from the filter, but so that it is contained. DPF ash should be considered a hazardous material, and should be handled in an appropriate manner.

Cleaning in a Nutshell

The cleaning process for a DP filter is as follows:

  • Heating the Filter: The filter must be heated before the accumulated debris can be removed.
  • Application of Compressed Air and Vacuum: Compressed air must be used to blow the collected matter out of the heated filter. However, that matter cannot be allowed to circulate in the environment – vacuum is used to trap and contain it.
Cleaning your filter requires the use of specialized equipment and tools. There are cleaning stations on the market, although they do represent a significant investment. This would make sense for operations where many diesel engines were present, and there was a significant need for regular DPF cleaning. However, for a company with only a few diesel engines, it makes more sense to hire a specialized cleaning company to perform the tasks.

In addition to following the right cleaning steps, you need to clean your filter at the right intervals. The EPA recommends cleaning the average DPF every six to 12 months. However, this is based on average usage and average particulate emissions. If yours are heavier, then you will need to clean the filter more frequently.

What about Downtime?

One of the most frequent objections to cleaning diesel particulate filters is that it forces the vehicle to be out of commission. That downtime represents lost productivity and profitability, and could result in delay to customers. To help prevent that from occurring, it’s recommended that you purchase multiple DPFs. This way, a clean filter can be installed in the vehicle and it can get back on the road while the dirty filter is being cleaned.

As you can see, maintaining your diesel particulate filter is a vital consideration. It can require downtime for your equipment, but with the right planning, that can be minimized or avoided. Follow the filter system manufacturer’s recommendations on service intervals and cleaning steps.