A diesel particulate filter is an emission control device found in the exhaust system of most modern diesel cars. Its main role is to collect and retain soot, which are tiny black particles produced when diesel fuel burns. These particles can degrade air quality and negatively impact people’s health.
How does a diesel particulate filter work?
DPF works by trapping harmful soot from exhaust gases using a wall-flow ceramic honeycomb structure. The porous walls trap soot particles while the cleaned gases exit through the other side. This reduces particulate emissions by 85-99%, depending on the system and driving conditions.
Over time, soot buildup can block the filter. To clean it, the DPF heats up and burns off the soot in a process called regeneration. To prevent this, the DPF burns off the soot through regeneration, either passively during longer drives or actively when triggered by the vehicle’s system.
Importance of DPF in diesel engines
Diesel Particulate Filters (DPFs) are essential for reducing over 80% of soot emissions, helping control air pollution and protect public health by limiting harmful particulate exposure. They are mandatory under India’s BS6 norms, and vehicles without a functioning DPF may fail emission tests or face penalties.
A clean DPF also improves engine efficiency by reducing exhaust back pressure, enhancing fuel combustion and torque. Neglecting DPF maintenance can lead to costly engine damage, which some car insurance plans may not cover, making regular upkeep important for both performance and smoother claim processing.
Components of diesel particulate filter
A diesel particulate filter is made up of several integrated components that work together to capture and remove soot from diesel exhaust gases.
- Filter structure: The core filtering element is a ceramic substrate with a wall-flow honeycomb design. The channels in the structure are sealed at alternate ends, which forces exhaust gases to pass through the porous channel walls.
- Filter materials: The common materials used for the substrate are cordierite and silicon carbide. These materials are selected for their thermal stability and resistance to the high temperatures generated during regeneration.
- Catalyst coating: Some DPFs are coated with a catalyst, usually made of platinum to improve passive regeneration by enabling soot oxidation at lower exhaust temperatures.
- Integrated catalysts: A Diesel Oxidation Catalyst (DOC) is integrated with the DPF in some systems. It helps raise the temperature of the exhaust gases and supports the oxidation of hydrocarbons and carbon monoxide before they reach the filter.
- Sensors and ECU: Differential pressure sensors and temperature sensors are positioned before and after the filter. These sensors provide input to the vehicle’s Electronic Control Unit (ECU), which calculates the soot load and determines when regeneration is required.
Tips to maintain a diesel particulate filter
Neglecting DPF maintenance can result in costly repairs and reduced vehicle performance. To keep it in shape, you need to:
- Use the right fuel and oil: Only use ultra-low sulphur diesel and manufacturer-approved engine oils. High-sulphur fuel or low-grade oil leads to excessive soot and ash accumulation.
- Avoid frequent short trips: Short drives don’t let the exhaust get hot enough for regeneration. Combine errands or take longer drives when possible.
- Drive at highway speeds regularly: Sustained speeds help trigger passive regeneration and burn off soot without intervention.
- Stick to the service schedule: Your vehicle’s manual outlines DPF maintenance intervals. Don’t skip them, especially if you notice a warning light.
- Use fuel additives wisely: Approved additives can help reduce soot, but avoid overusing them. Always follow the manufacturer’s guidance.
Common DPF problems and their solutions
DPFs are durable but not immune to issues. Here are the most common problems and how they can be addressed:
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Problem
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Cause
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Symptoms
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Solution
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Soot clogging
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Frequent short trips, excessive idling or failed regeneration
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DPF warning light, reduced power, increased fuel use
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Passive or active regeneration or DPF cleaning
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Ash accumulation
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Normal wear over time or using the wrong engine oil
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Similar to soot clogging, regeneration is ineffective
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Manual cleaning or filter replacement
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Damaged DPF core
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Overheating during regeneration or physical damage
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Loud exhaust, overheating, warning lights
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Full DPF replacement
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Sensor malfunctions
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Faulty pressure or temperature sensors
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False warning lights or failed regenerations
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Run diagnostics and replace faulty sensors
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Conclusion
Diesel particulate filters are now a standard feature in diesel vehicles, particularly with the implementation of BS6 regulations. What many drivers don’t realise is that a neglected DPF can also affect their car insurance. Some comprehensive car insurance plans may not cover damage caused by ignoring warning signs or failing to perform necessary maintenance. And with third party car insurance, engine-related issues like these aren’t covered at all.
FAQs
- What is DPF in diesel cars?
In diesel cars, the DPF helps clean the exhaust by burning off trapped soot.
- What is DPF issue in car?
It refers to filter blockage, which can trigger warnings or reduce engine power.
- What cars have DPF, and does it affect car insurance?
Most BS6 diesel cars have DPFs. Poor DPF upkeep may impact comprehensive car insurance claims, but not third party car insurance.
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