Diesel particulate filter (DPF)

Diesel Particulate Filter (DPF) guide: How it works, maintenance, and benefits

Diesel engines remain a popular choice for many businesses due to their fuel efficiency and durability. However, diesel exhaust contains particulate matter that can harm air quality and human health. A Diesel Particulate Filter (DPF) is a critical technology designed to reduce these emissions and ensure compliance with modern environmental standards.

This guide provides a detailed overview of DPFs, how they work, their maintenance requirements, and considerations for businesses and individuals choosing diesel vehicles.

What is a Diesel Particulate Filter (DPF)?

A DPF is a device fitted to the exhaust system of a diesel engine that captures soot and other particulate matter before it is released into the atmosphere. By trapping harmful particles, DPFs:

• Reduce air pollution

• Improve public health by lowering diesel exhaust exposure

• Help engines run more efficiently and last longer

DPFs are now standard on most modern diesel vehicles to meet stringent emission regulations, particularly in Europe.

How does a Diesel Particulate Filter work?

DPFs trap soot particles in a filter as exhaust gases pass through. Over time, the trapped soot must be burned off to maintain filter efficiency—a process known as regeneration.

Regeneration types

Passive regeneration

• • Occurs automatically when exhaust temperatures are high enough to burn off soot.

  • Typically happens during steady highway driving at speeds of 50mph or above for at least 20 minutes.

  • Simple and requires minimal driver intervention.

Active regeneration

• • Necessary when vehicles are used mainly for short trips or stop-and-go traffic, where exhaust temperatures remain too low for passive regeneration.

  • Involves injecting additional fuel into the engine to raise exhaust temperatures and burn off accumulated soot.

Consequences of incomplete regeneration

If a DPF does not regenerate:

• Soot accumulates, reducing filter efficiency

• Engine backpressure increases, lowering performance

• Emissions rise, potentially violating environmental regulations

Regular regeneration and maintenance are crucial to avoid costly repairs or engine damage.

DPF maintenance

To ensure optimal performance:

• Follow the manufacturer’s recommended maintenance schedule

• Monitor the vehicle for warning lights indicating DPF blockage

• Perform cleaning or replacement as required

• Use proper driving patterns (including occasional higher-speed journeys) to support passive regeneration

Types of Diesel Particulate Filters

1. Passive DPFs

• Utilise a ceramic filter coated with a catalyst.

• Regeneration occurs naturally at high exhaust temperatures.

• Generally less expensive and require minimal maintenance.

2. Active DPFs

• Incorporate a fuel injector to raise exhaust temperatures for more effective regeneration.

• More expensive but highly efficient at reducing emissions.

• Often required for vehicles operating in urban environments or with frequent short trips.

Benefits of Diesel Particulate Filters

DPFs provide multiple advantages, including:

• Reduction in harmful particulate emissions

• Improved urban air quality

• Lower health risks for drivers and the public

• Reduced engine wear and extended vehicle lifespan

• Compliance with modern emission regulations

Challenges and considerations

While DPFs are essential for emission control, there are challenges to consider:

• Cost: Installation and replacement can be expensive

• Maintenance: Requires regular monitoring and periodic regeneration

• Cold Weather: Less effective in cold climates, potentially increasing emissions

• Short Journeys: Vehicles primarily driven in urban traffic may require active regeneration or additional maintenance

• Residual Values: Diesel vehicles may have fluctuating resale value due to emission regulations

Who should and shouldn’t choose a diesel vehicle?

Suitable for:

• Businesses or individuals with long-distance, highway-heavy driving patterns

• Rural or intercity operations where diesel efficiency outweighs urban emissions concerns

• Operators seeking fuel economy and high torque for heavy payloads

Not ideal for:

• Urban fleets with short, stop-start journeys

• Businesses concerned about low-emission zones (ULEZ, LEZ) in cities

• Drivers seeking a fully zero-emission vehicle

For urban and short-distance use, hybrid or electric vehicles may be a more practical, cost-effective, and environmentally friendly option.

Alternative vehicles

For businesses or drivers operating mainly in congested areas:

• Electric vans or cars – zero tailpipe emissions, lower running costs, government incentives

• Plug-in hybrids (PHEVs) – reduced emissions with the flexibility of a petrol engine

• Hybrid vehicles – suitable for mixed urban and suburban driving

We’re here to help

Choosing the right vehicle is critical for operational efficiency and compliance. Our team at Commercial Vehicle Contracts can help you:

• Understand whether a diesel, hybrid, or electric vehicle is best for your fleet

• Provide detailed guidance on DPF maintenance and operation

• Advise on incentives, costs, and long-term considerations

Contact us today to discuss your requirements and ensure you make an informed, environmentally responsible choice for your business.

 Call our expert team: 01424 863 456 for friendly, no-obligation advice.

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