There’s no such thing as a good time for downtime, especially when it’s unexpected. And one issue many fleet drivers don’t plan for is forced regens.

If you haven’t experienced this issue yet, consider yourself lucky. A forced regen occurs when soot builds up inside the diesel particulate filter (DPF) to the point that the vehicle is no longer operable. When this happens, a driver has to pull over and initiate a self-cleaning process that can take up to 40 minutes — valuable time that could have been spent on the road.

But forced regens don’t have to be the problem they are for some fleet drivers. With one simple change, forced regens can be reduced, helping you keep your rigs on the road and in service.

Why regens occur in diesel vehicles

To get the upper hand over forced regens, it’s important to understand some mechanics. The type of soot buildup that creates the need for a regen occurs inside a specialized component of the exhaust system called the diesel particulate filter (DPF).

In recent years, DPFs have become common in diesel-powered equipment as a means of controlling emissions. As part of the most recent additions to the Clean Air Act, medium- and heavy-duty trucks are required to meet stricter emissions standards. To satisfy the mandate, the industry began more broadly implementing DPFs to trap soot inside a vehicle before it can be released into the air, thus reducing harmful emissions. 

What happens during a regen

To prevent clogging, DPFs clean themselves from time to time by burning off accumulated soot. This process is referred to as regeneration, because the DPF is working to “regen” itself to its original state.

When everything is working as it should, regeneration occurs automatically while the vehicle is in motion, unnoticeable to the driver. Using the heat of the exhaust itself, soot is burned off the DPF often as quickly as it accumulates. This is known as passive regeneration.

In cases where the exhaust isn’t hot enough to burn off soot on its own, the vehicle can inject fuel into the DPF, thereby raising the temperature to burn away soot. This form of regeneration, known as active regeneration, is also typically unnoticed by the driver, though it will result in a loss of power and performance while the regen occurs.

The trouble begins when a passive or active regeneration isn’t enough to burn away soot. In these cases, a forced regen is required and a driver has to pull over and wait while the DPF completes a more rigorous self-cleaning process. Failure to perform a forced regen when notified by your vehicle’s indicator system can cause severe engine damage.

How to reduce forced regens

The good news is that forced regens don’t have to be a recurring nuisance if drivers reduce impurities entering into the DPF at the start.

A premium diesel fuel like CENEX ROADMASTER XL® can reduce the need for DPF regeneration. With an enhanced additive package engineered to meet the demands of today’s high-performance diesel engines, Cenex Roadmaster XL keeps engines running cleaner, stronger and longer than ever before, even in the toughest conditions. The enhanced formula is 25% more effective in reducing exhaust cylinder temperature deviations, in comparison to the previous generation.  Reduced exhaust cylinder temperature deviations are a key indicator that the equipment is benefitting from improved fuel efficiency and lead to increased equipment power. The complete, clean, balanced combustion means there will be less soot produced, leading to a reduction in regenerations.

With evolving emissions mandates affecting rigs beginning with model year 2027 and beyond, DPFs will likely continue their role in the industry for the foreseeable future.
Learn more about how Cenex Roadmaster XL can keep your DPF clean and your operation moving with a visit to

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