DPF regeneration: How to keep your diesel particulate filter in top shape

Did you know that a clogged diesel particulate filter (DPF) can not only significantly impair the performance of your vehicle, but can also lead to expensive engine damage? It’s hard to imagine modern diesel vehicles without a functioning DPF. It plays a key role in reducing pollutant emissions and ensures that your vehicle complies with strict emissions standards. In this comprehensive guide, you will learn everything you need to know about DPF regeneration: how to start it, when it takes place and whether regeneration is possible when the vehicle is stationary. With practical tips and in-depth specialist knowledge, we will help you to maintain your particulate filter efficiently and avoid expensive repairs.

What is a diesel particulate filter (DPF)?

Function and meaning

The diesel particulate filter, often simply referred to as DPF, is an essential component of the exhaust system of modern diesel vehicles. Its main task is to filter soot particles from the exhaust gases produced during the combustion of diesel. These soot particles are harmful to health and contribute to fine dust pollution in the air. By using a DPF, up to 90 % of these particles are retained, which not only protects the environment, but also contributes to compliance with statutory emission standards.

Structure of the DPF

A DPF usually consists of a heat-resistant stainless steel housing in which a ceramic or silicon carbide filter element is housed. This filter element has a honeycomb structure with microscopically small channels. The walls of these channels are porous and trap the soot particles as the cleaned exhaust gases flow through. Over time, however, soot accumulates in the filter, which can lead to clogging if regular regeneration does not take place.

Legal regulations

The introduction of the diesel particulate filter was largely driven by stricter emissions standards. DPFs have been mandatory for all new diesel vehicles registered in Germany since 2009. The Euro 6 standard, which has been in force since September 2015, sets particularly strict limits for particulate emissions. Without a functioning particulate filter, it would be almost impossible to comply with these standards.

Why is DPF regeneration important?

Effects of a clogged DPF

A clogged particulate filter can have a significant negative impact on your vehicle. First of all, you may notice a significant loss of power. The engine seems powerless and accelerating is more difficult than usual. This is because the exhaust back pressure in the clogged DPF increases and the engine has to work harder to expel the exhaust gases. Another effect is increased fuel consumption, as the engine works more inefficiently.

In the long term, a clogged DPF can lead to serious engine damage. The increased thermal load can damage components such as the turbocharger. There is also a risk of unburned fuel getting into the engine oil, which impairs the lubricity of the oil and leads to increased wear.

Environmental aspects

In addition to the technical problems, a malfunctioning DPF also has a negative impact on the environment. Without sufficient filtration, large quantities of fine dust are released into the atmosphere. These ultra-fine particles can penetrate deep into the lungs and cause health problems. A functioning DPF is therefore crucial not only for your vehicle, but also for the environment and public health.

Economic aspects

The cost of replacing a diesel particulate filter can be between 1,000 and 4,000 euros, depending on the vehicle model. There are also labor costs for installation. Regular regeneration and maintenance can significantly extend the service life of your DPF and avoid expensive repairs. It therefore makes economic sense to familiarize yourself with the operation and maintenance of the particulate filter.

Types of DPF regeneration

Regeneration of the diesel particulate filter is a process in which the accumulated soot is burned off in order to maintain the filter performance. There are different types of regeneration:

Passive regeneration

Passive regeneration takes place automatically during normal driving, especially on long journeys on the highway. Here, the exhaust gases reach temperatures of over 350 °C. These high temperatures are sufficient to burn off the accumulated soot in the DPF and convert it into ash. This process takes place unnoticed and requires no intervention by the driver.

Active regeneration

If the driving profile does not allow sufficient temperatures – for example during frequent short journeys – the engine control unit initiates active regeneration. During this process, additional fuel is injected in a targeted manner, which burns in the exhaust tract and increases the temperature to around 600 °C. This allows the soot in the DPF to burn off. This allows the soot in the DPF to burn off. During active regeneration, fuel consumption may increase and the engine may run somewhat more smoothly.

Forced regeneration

In cases where the DPF is heavily clogged and neither passive nor active regeneration has been successful, a DPF forced regeneration can be carried out in the workshop. The regeneration process is started manually using a diagnostic tool. The engine runs at a higher speed when stationary in order to achieve the necessary exhaust gas temperatures. This method should only be carried out by qualified personnel, as it involves risks such as engine overheating.

Additive-assisted regeneration

Some vehicle manufacturers use an additive system in which a special additive is mixed into the fuel. This additive lowers the combustion temperature of the soot so that regeneration can already take place at lower exhaust gas temperatures. Vehicles from Peugeot and Citroën, for example, use this system. However, the additive tank must be topped up regularly, which requires additional maintenance.

Signs of a full or clogged DPF

It is important to recognize the warning signals that indicate a full or clogged particulate filter. The sooner you react, the easier it will be to rectify the problem.

Warning signals in the cockpit

Most modern vehicles are equipped with sensors that monitor the condition of the DPF. If there are problems, warning symbols light up on the dashboard:

• DPF warning light: Indicates directly that the particulate filter has a high soot load.
• Check engine light: General warning signal that can also indicate problems with the DPF.
• Service display: Some vehicles display a message such as “Regenerate DPF” or “Check particulate filter”.

Changes in vehicle behavior

In addition to the warning lights, changes in driving behavior can also indicate a full DPF:

• Loss of power: The vehicle reacts more slowly to accelerator commands.
• Jerking or uneven engine running: Especially when accelerating.
• Difficulties starting the engine: The engine is harder to start than usual.

Increased fuel consumption

A clogged DPF increases the exhaust back pressure, which means the engine needs more fuel to achieve the same performance. If you notice unusually high consumption, this could be an indicator.

Unusual noises and odors

• Whistling noises: May indicate leaks in the exhaust system caused by increased pressure.
• Burnt smell: Indicates overheated components in the exhaust tract.

Causes of problems with DPF regeneration

Various factors can cause the regeneration of the particulate filter not to function properly.

Short trips

The engine does not reach the necessary operating temperature during frequent short journeys. The exhaust gases remain too cold to burn off the soot in the DPF. Regeneration is either not started at all or is constantly interrupted, which leads to a build-up of soot.

Example: If you only drive a few kilometers a day in the city, the engine barely reaches its optimum temperature. Passive regeneration will not take place and active regeneration may be interrupted before it is completed.

Defective sensors and components

Particle filter differential pressure sensor: This sensor measures the pressure difference before and after the DPF. A defect means that the engine control unit does not receive correct information about the load status of the filter and does not initiate regeneration.

Lambda sensor: It measures the oxygen content in the exhaust gas and influences the formation of the fuel-air mixture. If the values are incorrect, combustion can be inefficient, leading to more soot formation.

EGR valve (exhaust gas recirculation valve): A defective EGR valve can lead to increased soot formation as the exhaust gas recirculation does not function correctly.

Low quality fuel or engine oil

The use of low-quality diesel or the wrong engine oil can increase soot formation. Special additives in the fuel are missing or are of poor quality, which makes combustion inefficient.

Incomplete combustion

Defective injectors or spark plugs (in petrol engines with particulate filters) can lead to incomplete combustion. This increases the amount of unburned hydrocarbons and soot in the exhaust gas.

Step-by-step guide to DPF regeneration

If your vehicle indicates that regeneration of the particulate filter is required, you can take action yourself.

Preparation

1. Check the fuel level: Make sure that the tank is at least a quarter full. Some vehicles do not start regeneration when the fuel level is low.
2. Check the AdBlue level: Sufficient AdBlue is required for vehicles with an SCR catalytic converter.
3. Read out the fault memory: Have the fault memory read out by a workshop to ensure that there are no other problems.

Carrying out a regeneration trip

A regeneration drive is necessary to burn out the particulate filter:

• Choose a route: Look for a route on which you can drive constantly, ideally a highway or a country road with little traffic.
• Speed and rpm: Ride at a speed of over 60 km/h for at least 15 to 30 minutes. Keep the engine speed between 2,000 and 2,500 rpm. This allows the engine to reach the necessary exhaust temperatures.
• Avoid interruptions: Stop-and-go traffic or frequent stops prevent successful regeneration.
• Monitor the vehicle: Pay attention to unusual noises or warning messages.

Follow-up

• Check the warning lights: If the DPF warning light goes out, the regeneration was successful.
• Read out the fault memory again: If problems persist, you should have the fault memory checked again.
• Plan regular journeys: Integrate such regeneration rides regularly into your driving schedule, especially if you frequently drive short distances.

Tips for extending the DPF service life

Proactive maintenance of your particulate filter can significantly extend its service life and avoid expensive repairs.

Regular maintenance

Adhere to the maintenance intervals specified by the manufacturer. Regular oil changes with the engine oil approved by the manufacturer are crucial. Only use low-ash oils (low-SAPS) that are suitable for vehicles with DPF.

Use of high-quality fuel and engine oil

High-quality diesel contains additives that improve combustion and reduce soot formation. Avoid cheap fuels of unknown origin.

Adapt driving behavior

• Combine short and long journeys: Plan longer journeys regularly to give the DPF the opportunity to regenerate.
• Avoid frequent cold starts: If possible, do not run the engine when it is cold. However, please note that warming up the engine while stationary is not permitted.

Monitoring the sensors

Have the exhaust system sensors checked regularly. Defective sensors can be detected at an early stage and replaced before major damage occurs.

Common problems and solutions: What to do if DPF regeneration fails?

A diesel particulate filter (DPF) should regenerate itself regularly. But what happens if the regeneration run is not successful? The following causes are often responsible:

• Defective sensors: A faulty differential pressure sensor or a defective lambda sensor can provide incorrect values and prevent regeneration. A diagnosis in the workshop provides clarity.
• Severe clogging: If the soot load is already too high, a normal regeneration drive is no longer sufficient, as the temperatures are not high enough to burn off the soot completely.

Solutions for a clogged DPF:

• Professional cleaningAdvanpure offer a thorough cleaning of the filter to remove soot and ash residues. This extends the service life and restores the function.
• DPF forced regeneration: Forced regeneration can be carried out in our workshop. However, this method should only be used by qualified personnel in order to avoid damage.

Error codes and their meaning: take warning signals seriously

Modern vehicles store error codes in the control unit if the DPF is causing problems. The following codes occur particularly frequently:

• P2002: The efficiency of the DPF is below the permissible threshold value. The filter is no longer working optimally and could be clogged.
• P242F: The ash load is too high so that regeneration is no longer possible. Cleaning or replacement is necessary.

A fault memory readout in the workshop provides information on what action is required.

Particle filter cleaning or replacement: When is which measure sensible?

• Cleaning: Useful if the filter is not damaged and the ash load has not yet reached the critical range. Professional cleaning can restore full functionality.
• Replacement: Necessary if the DPF is cracked, melted or has other mechanical damage. In this case, cleaning is no longer possible.

Manufacturer-specific features

DPF regeneration for various brands

Volkswagen (VW): A DPF warning light comes on in many models. A regeneration drive according to the operating instructions is recommended.

BMW: relies on a combination of active and passive regeneration. Some models can carry out regeneration while stationary, but this cannot be initiated by the driver.

Peugeot and Citroën: Use an additive system (Eolys) that lowers the combustion temperature of the soot. The additive tank must be topped up regularly.

Manufacturer recommendations

Read the operating instructions for your vehicle carefully. There you will find specific instructions on DPF regeneration and correct driving behavior.

Warranty and service

A clogged DPF is generally not covered by the manufacturer’s warranty, as it is considered a wearing part. However, regular maintenance and compliance with the manufacturer’s instructions can help to safeguard warranty claims for other components.

Environmental and health aspects

Effects of soot particles

Soot particles from diesel engines are among the fine dust emissions that are harmful to health. They can cause respiratory diseases, cardiovascular problems and even cancer. A functioning DPF significantly reduces these particulate emissions.

Statutory emission limits

With the Euro 6 standard, the EU has set strict limits for pollutant emissions. Vehicles without a functioning DPF cannot comply with these limits and may therefore not be operated.

Contribution to air quality

By ensuring that the particulate filter functions properly, you are making an important contribution to improving air quality and protecting the environment.

Cost analysis: cleaning or replacement – which is worthwhile?

The cost of a diesel particulate filter cleaning varies depending on the method and provider. A professional cleaning, in which the DPF is thoroughly freed from soot and ash residues, costs €299.

However, if the filter is so badly damaged or clogged that cleaning is no longer sufficient, the only option is to replace it. Depending on the vehicle model, a new DPF can cost between 1,000 and 4,000 euros – plus the labor costs for installation and removal.

In view of these figures, it is clear that timely regeneration and professional cleaning is the more economical option. Those who act early not only save high replacement part and repair costs, but also protect the engine and exhaust system from expensive consequential damage.

FAQ – Frequently asked questions

How do I start the DPF regeneration?

You can support regeneration by taking a longer ride at a constant speed. Drive for at least 15 to 30 minutes at over 60 km/h and keep the engine speed between 2,000 and 2,500 rpm. This enables the engine control unit to initiate active regeneration.

When does DPF regeneration start?

Regeneration starts automatically if certain conditions are met: sufficient operating temperature, a certain degree of soot loading of the DPF and no active faults in the system. The engine control unit continuously monitors these parameters.

Can a DPF be regenerated while stationary?

Regeneration at a standstill is generally not possible as the necessary exhaust gas temperatures are not reached. However, some workshops can carry out a forced DPF regeneration in which the engine is brought up to a higher speed when stationary. This should only be carried out by qualified personnel.

Does the use of DPF additives make sense?

Additives can support regeneration, but do not replace the need for a regeneration drive. They lower the combustion temperature of the soot and can be particularly helpful for vehicles that frequently drive short distances. It is important to only use additives that have been approved by the manufacturer.

What happens if I ignore the warning lights?

If you ignore the warning signals, you risk considerable damage to the engine and exhaust system. A clogged DPF can lead to increased exhaust back pressure, which can damage the turbocharger and other components. It can also lead to expensive repairs and fines for exceeding the emission limits.

How does the DPF differ between diesel and gasoline vehicles?

While the DPF is widely used for diesel vehicles, modern gasoline vehicles with direct injection often have an Otto Particulate Filter (OPF). They work in a similar way, but the particulate emissions are generally lower in petrol vehicles.

Practical tips and advice

Checklist for drivers

• Regular long-distance journeys: Integrate trips on the highway into your daily routine.
• Take warning signals seriously: React immediately to warning lights and unusual driving behavior.
• Use high-quality fuel: Give preference to filling stations with quality fuel.
• Check the engine oil: Make sure the oil level is correct and only use approved oils.

Choosing the right workshop

Look for a workshop that has experience with DPF systems. Ask for references and find out about the services they offer, such as professional DPF cleaning.

Use of diagnostic apps

With OBD-II scanners and corresponding apps, you can carry out basic diagnostics and read out fault codes yourself. This gives you an initial overview of the condition of your vehicle.

Summary and conclusion

Regenerating the diesel particulate filter is an essential process for maintaining the performance of your vehicle and preventing environmental damage. A clogged particulate filter can lead to considerable technical problems and high costs. By adapting your driving behavior, carrying out regular maintenance and reacting to warning signals at an early stage, you can extend the service life of your DPF and avoid expensive repairs.

Further resources

• Manufacturer’s manuals: Detailed information can be found in the operating instructions for your vehicle.
• Specialist workshops: Get advice from experts and take advantage of professional services.
• Online forums and communities: exchange ideas with other drivers and benefit from their experiences.

Legal information and disclaimer

The information provided in this article has been carefully researched and checked. However, we cannot guarantee that the content is correct, complete and up to date. In the event of technical problems or uncertainties, please contact a qualified specialist workshop.