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The Best Answer to a $1,400 Question

Everyone involved with the trucking industry over the last decade has probably had to replace a Diesel Particulate Filter (DPF), either because it became too plugged to clean or because it started to crack and wouldn’t perform properly. Faced with a bill totaling thousands of dollars for a single part, it’s understandable that many truckers might look for a cheaper “will-fit” alternative.

Cummins research and development team did a thorough technical analysis of a “will-fit” competitor, to see what type of impact putting a non-genuine DPF in the exhaust system would have on engine performance, reliability and durability. What they found was that using a “will-fit” DPF could lead to engine damage and wind up costing you more in the long run.

Excess Backpressure

Testing showed that improper sizing of channels, together with rapid accumulation of soot, will typically result in higher backpressure – which in turn can cause premature turbocharger wear and failure.

Backpressure Comparison Graph: DPF Backpressure X Exhaust Flow

Significant differences in cell wall thickness, cell density and wall pore size can also reduce the open frontal area, restricting exhaust flow and resulting in a significant loss in fuel economy and a corresponding rise in operating costs.

Increased DEF and Fuel Consumption

Something that is not visible to the naked eye is precious metal content, which is critical for the catalytic reactions that take place in the DPF. The “will-fit” DPFs tested did not meet specifications for content or distribution. This can lead to significant consequences downstream in the Selective Catalytic Reduction portion of the aftertreatment system, leading to increased service, excess downtime and lost revenue. The lack of precious metal in the “will-fit” units causes them to be less efficient at converting hydrocarbons (HCs) and oxides of nitrogen (NOx) than the Genuine Cummins DPF. This has the potential to trigger fault code lamps and increase consumption of Diesel Exhaust Fluid (DEF).

Too Many Regenerations.

The Genuine Cummins DPF has more than 3.75 times the soot capacity as the non-genuine DPF tested. As a result, “will-fit” DPFs experienced nearly double the number of active regeneration events. With each regeneration event raising exhaust temperatures in excess of 1000 degrees Fahrenheit, there was increased metal fatigue on the exhaust pipes and canister, plus an increased risk of DPF cracking and/or melting.

Soot Loading Capacity Graph: DPF Backpressure X Exhaust Flow

Furthermore, the non-genuine DPFs were more difficult to clean – so soot buildup happens faster, requiring more frequent maintenance.

Hidden Costs vs. The Right Choice.

The bottom line? At the end of the day, buying a single Genuine Cummins DPF versus two “will-fit” DPFs will save you close to $1,400 over the same time period and mileage ($2,000 versus $3,400 at today’s prices). Of course, that’s just the parts cost. It doesn’t even take into account labor costs, downtime, or the hassle and inconvenience involved. Customers may save $600 initially – but it’s going to cost double or triple that amount down the road.

For additional details, including test results showing the difference between Genuine Cummins and “will-fit” DPFs, visit

*Remanufactured DPFs are not for sale in California.

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