While the diesel particulate filter itself requires little maintenance, proper attention to related systems will help avoid problems.

The compact Volvo and Mack DPF fits comfortably behind the step on the passenger side door.

The U.S. Environmental Protection Agency’s 2007 emissions standards required a reduction in both diesel particulate and nitrogen oxides. The new particulate standard was so low that, even with advanced injection and air handling systems, a particulate filter was needed to bring exhaust soot levels down to required levels.

The porous ceramic filter under normal, over-the-road driving conditions burns off the soot it collects and does not require frequent maintenance. However, it still has to be cleaned periodically because some ash ends up in the filter.

“The regeneration of soot in the DPF does not form ash buildup or any residue in the DPF,” says Zack Ellison, director of customer technical support at Cummins. “Ash collected in the DPF is primarily caused by sulfated ash (TBN) in the oil.” Ash, which results from burning of a small amount of lube oil, does not burn, even at temperatures that burn off soot, and must be cleaned up.

While certain specific DPF-related maintenance tasks are required, both the vehicle’s maintenance and its operation have a significant effect on DPF performance. Therefore, running a 2007 or later model truck will keep you on your toes. The payback could be lower costs since your equipment will last longer, run better and fetch a higher resale value.

While the filter burns off soot as fast as it collects under normal highway driving conditions, soot will accumulate during idling or while crawling through traffic. In response, you have to actuate a fuel dosing system to clean the DPF, a process called active regeneration. Warning lamps on the dash will indicate the need for active regeneration or ash cleaning. Which lamp turns on depends on how fast backpressure is building up in the DPF, as soot accumulates much faster than ash.