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How to Maintain Diesel Particulate Filter (DPF) Systems

Knowing how to maintain diesel particulate filter systems is important for an engine’s life and performance. Diesel particulate filters trap the ash from motor oil and soot from exhaust in trucks with a diesel engine. The built-up soot burns off during most trucks’ normal operations. Ash will stay in the filter’s honeycomb, and you should include its removal in routine maintenance. A process called “passive regeneration” will burn off with the heat from the truck’s exhaust. Trucks that work in a stop-and-go operation, or that idle a lot, however, rarely get hot enough to burn off the soot. In that instance, the soot must be actively burned off in the filter. Injecting extra fuel upstream from an oxygen catalyst, or plugging in an electric heater while parked, is how to burn it off.


Active soot removal through on-board regeneration can take place several times a day depending on the truck’s operation. An indicator light on the dash will alert the driver to the need for removal. If it goes unnoticed, the warning light will become more active, and the driver will have to stop to begin an active regeneration.


Ash from the motor oil stays in the filter and requires removal by blowing it out with air or washing it. The process to clean the DPF starts by removing it from the truck and putting it in a special machine. The machine sends compressed air through the filter in a series of blasts. The other process involves pressure washing the filter with de-ionized water and drying it. A filter can hold anywhere from 7 to 21 ounces of ash, depending on how long it’s been since the last cleaning.


You should remove excess ash every 100,000 miles or 3,000 hours, whichever comes first. A warning light on the dash will also warn the driver of the impending milestone. On occasion, an engine will produce more soot or expel unburned motor oil. The DPF will catch this too, but it can’t burn it off during the normal process. When this happens, you’ll need to remove the substrate from the DPF and thoroughly clean it. A special machine heats the substrate and burns off the excess material.


If you need your DPF system cleaned or inspected, visit our service department. For all your OEM Isuzu commercial truck parts and needs, contact HFI Truck Center today, or visit our website.