How To Unblock A DPF

Author: Jesse Bentley   Date Posted:22 May 2024 

How To Unblock A DPF main image How To Unblock A DPF image

Blocked DPF? Here Are Your Solutions

Understanding Diesel Particulate Filters (DPF)

Diesel Particulate Filters (DPFs) are crucial for modern diesel engines. They capture and store exhaust soot and ash in a ceramic honeycomb substrate. During regeneration, these particulates are burned off. However, when the DPF doesn't reach the necessary temperature to burn off the trapped soot and ash, these particulates accumulate, leading to performance issues, reduced power and torque, and increased harmful emissions.

Diagnosing a Blocked DPF

Common signs of a blocked DPF include increased fuel and oil consumption, poor engine performance, reduced turbo performance, increased idle speed, and warning lights for "Check Engine" or "DPF." The severity of the blockage can be determined using a back-pressure test tool like the JLM Manometer, a compact, digital instrument that measures automotive pressure sensors.

Solutions for Small Blockages

For blockages up to 30mbar, using a JLM Diesel DPF Cleaner is effective. This cleaner not only targets the soot filter but also reduces particulate matter, hydrocarbons, carbon monoxide, and soot emissions. Simply pour the JLM DPF cleaner into your diesel fuel tank for preventive maintenance.

For blockages around 30mbar, the JLM Diesel DPF Cleaner Heavy Duty is recommended, especially for trucks and commercial fleets. This cleaner has a higher concentration of active additives and also conditions the engine and DPF, enhancing performance and reducing fuel consumption.

Solutions for Medium Blockages

Blockages up to 80mbar can cause emission test failures. The JLM Diesel DPF Spray, available in an aerosol can, contains a high concentration of active ingredients. It cleans and regenerates blocked DPFs by lowering the combustion temperature of particulates, enabling earlier and faster combustion at lower engine temperatures. To use, spray the JLM Diesel DPF Spray into the particulate filter before forced regeneration.

Solutions for Heavy Blockages

For blockages exceeding 80mbar, the JLM Diesel DPF Cleaning Toolkit is the most potent option. Paired with the JLM Diesel DPF Cleaning & Flush Fluid Pack, it employs a two-step method to loosen and remove soot. The pre-soaking cleaner loosens soot and grease, and the flush fluid removes the loosened particulates, allowing for effective regeneration during forced regeneration.

Solutions for Very Heavy Blockages

Very heavy blockages necessitate removing the DPF and having it cleaned at a professional station. The cleaning process involves high-pressure water mixed with Hydro Carbon fluid and blasts of air to remove soot and ash. After cleaning, a full drying process at 100°C ensures no moisture remains, preventing sensor issues and further blockages.

Prevention Tips

To prevent DPF blockages, use a DPF additive like JLM Diesel DPF ReGen Plus. This additive supports the regeneration process, ensuring more complete oxidation of soot and improved DPF performance. It's particularly beneficial for vehicles making short journeys or frequently operating at low speeds.


Maintaining your DPF is essential for optimal engine performance and reducing harmful emissions. Whether addressing small, medium, or heavy blockages, using the appropriate cleaning solutions and preventive additives can significantly extend the life of your DPF and enhance your vehicle's efficiency.


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