Diesel Particulate Filters (DPF) Guide

Welcome to our comprehensive guide on Diesel Particulate Filters (DPF). DPFs are a critical element in modern diesel engines, designed to reduce harmful emissions and protect the environment. Nevertheless, they can also cause problems if not correctly maintained or used.

In this guide, GB Vehicle Leasing cover everything you should know about DPFs, such as their functioning, common problems, maintenance tips, and more. So, let's dive into the topic and learn all about Diesel Particulate Filters.

What is a diesel particulate filter?

A diesel particulate filter (DPF) is a device installed in the exhaust system of diesel-powered vehicles to capture and remove particulate matter (PM) from the exhaust gases. PM is a mixture of tiny, harmful particles that can cause respiratory problems and contribute to air pollution. The DPF traps the PM as it flows through the exhaust system, preventing it from being released into the atmosphere. As time passes, the trapped PM accumulates and must be burned off or removed via a process known as regeneration.

Do all diesel cars have a DPF?

In the UK, all diesel cars manufactured after September 2009 must have a DPF fitted as standard. However, some models may also have been installed with DPFs prior to the mandatory implementation in 2009.

It is against the law to remove the DPF from your car, and doing so can result in significant penalties. Additionally, if a DPF was originally installed in a vehicle during production and is absent during an MOT test, the vehicle will fail the test.

What is a DPF regeneration system?

A DPF regeneration system is a mechanism in modern diesel engines designed to automatically clean the diesel particulate filter (DPF) by burning off the trapped soot particles. There are two types of DPF regeneration systems: passive and active.

Passive Regeneration

Passive regeneration occurs naturally as the vehicle is driven at high speeds for an extended period, which raises the exhaust temperature and triggers the regeneration process. During this process, the soot particles in the DPF are oxidized, converting them into carbon dioxide and water vapor. Passive regeneration is the most common type of regeneration and occurs frequently in vehicles used for long trips or high-speed driving.

Active Regeneration

Active regeneration occurs when the soot buildup in the DPF reaches a certain level that cannot be burned off during normal driving conditions. In this case, the engine management system will initiate an active regeneration process, which involves injecting diesel fuel into the exhaust system to increase the temperature of the DPF and burn off the trapped soot particles. Active regeneration is typically initiated when the engine is running at a constant speed and can take up to 30 minutes to complete.

Both passive and active regeneration systems are essential in maintaining the efficiency of the DPF and reducing harmful emissions. However, if the DPF cannot regenerate properly due to blockage, it may lead to further problems and require manual cleaning or replacement.

Is my diesel particulate filter blocked?

A blocked diesel particulate filter (DPF) can cause several symptoms that indicate a problem. Here are some common symptoms of a blocked DPF:

• Loss of power: A blocked DPF can restrict the flow of exhaust gases, causing a reduction in engine power.

• Increased fuel consumption: The restricted flow of exhaust gases can also cause the engine to use more fuel than usual.

• Warning lights: A blocked DPF can trigger warning lights on the dashboard, such as the engine management light or DPF warning light.

• Smoke: A blocked DPF can cause excessive smoke from the exhaust, especially during acceleration.

• Regeneration problems: If the DPF cannot regenerate properly due to blockage, it may lead to regeneration problems, including failed regeneration attempts or incomplete regeneration.

If you experience any of these symptoms, it is important to get your DPF checked by a qualified mechanic to avoid further damage to your engine and DPF system.

What is the frequency for cleaning a DPF?

The frequency of cleaning a DPF depends on several factors, including the vehicle usage, driving style, and the quality of the diesel fuel. Generally, most modern diesel engines have a DPF regeneration system that can clean the filter automatically as long as the vehicle is driven regularly at high speeds for an extended period. This allows the filter to reach a high enough temperature to burn off the trapped soot particles and regenerate itself.

However, if the vehicle is mostly driven in urban areas with frequent stop-and-go traffic, the DPF may not regenerate properly, leading to blockage over time. In such cases, the DPF may need to be cleaned manually by a qualified mechanic or replaced entirely.

In general, it is recommended to have the DPF inspected every 6-12 months or every 10,000 to 15,000 miles, depending on the vehicle usage and driving conditions. It is also essential to follow the manufacturer's recommended maintenance schedule and use high-quality diesel fuel to prolong the life of the DPF.

We hope this guide has provided you with valuable information on DPFs and the regeneration process. For more guides and news relating to cars, follow us on Facebook. In particular, view our related article - What is AdBlue? This explores what AdBlue is made of, and why it's essential for modern diesel vehicles.