A diesel particulate filter (DPF) is a component within a heavy-duty truck’s aftertreatment system. The filter’s purpose is to trap particulate matter that a diesel engine outputs to meet the standards set by the United States Environmental Protection Agency (EPA).
Like most filters, a DPF has a finite lifespan and requires cleaning to remain effective and, eventually, replacing. Regenerations are necessary to prevent particulate matter from quickly accumulating and rendering the DPF ineffective.
What is a DPF Regeneration?
Often shortened to “regen,” a DPF regeneration is the act of the system burning off collected particulate matter and turning it into ash. Eventually, the DPF system needs cleaning when ash levels are too high but regens significantly extend the amount of time before a technician intervention is necessary.
There are three types of regenerations to consider:
1. Passive Regeneration
When the aftertreatment system is working effectively and the vehicle has met the necessary conditions, a regeneration occurs while the truck is in transit.
Passive regeneration happens frequently in long-haul trucking because it requires continuous driving where the DPF can hit a temperature above 1,000 degrees Fahrenheit to create the heat levels that turn soot into ash.
2. Active Regeneration
Trucks that drive local routes and rarely maintain typical highway speeds for extended periods rarely meet the conditions for a passive regeneration.
In these cases, an active regeneration occurs. Rather than naturally occurring when the DPF reaches the high temperature on its own, the engine undergoes a process to increase exhaust heat and create a chemical reaction that generates the temperatures needed to oxidize particulate matter.
3. Forced Regeneration
The third type of regeneration has the aftertreatment system undergo a similar process to an active regeneration, but rather than the vehicle triggering the regen, it requires action from a third party, typically a driver or technician.
The Importance of Regenerations
A DPF Filter that is too full or not properly functioning threatens both the environment and the truck. The engine can derate when a needed regen does not occur, potentially causing downtime by leaving the vehicle in a state that is either undriveable or in “limp mode” where it can only operate at slow speeds.
In some instances, forced regeneration is the correct action to fix the problem. Still, in others, the DPF may need cleaning or replacing, and it’s important for technicians to perform the correct action.
When to Avoid Regeneration
There are plenty of instances where the DPF or other component of an aftertreatment system is triggering an active fault but a forced regen is not the answer. These include cases where cleaning or replacing the DPF is required or an entirely different component of the aftertreatment system causes the fault.
Consider the following cases for how JPRO Diagnostic Software helps technicians avoid a forced regen when it is not the recommended action:
1. Fault Descriptions
JPRO displays enhanced OE-level fault descriptions to guide users toward the root cause of the problem. Read the entire description and do not assume a mention of the word “Filter,” “DPF,” “SCR,”or “Aftertreatment” means a forced regen is the solution.
These components can present a variety of issues with different solutions for each, so further research is needed to determine if the forced regen is the answer.
A DPF system relies on many sensors working correctly. If any of these sensors has an issue that triggers a fault code, a regen will not fix the problem without first isolating and repairing the malfunctioning sensor.
2. Aftertreatment Checklist
JPRO’s aftertreatment diagnostics feature presents users with the values, data, visuals, and features needed to diagnose and begin repairing aftertreatment issues.
Upon opening the feature, users view a checklist of items to inspect visually. By following this list, technicians can often correct the problem without the need to force a regen.
3. Regen Zone Information
Perhaps the most significant indicator of the necessity of a forced regen is JPRO’s regen zone information.
Available within the Aftertreatment Diagnostics feature, technicians quickly see which regen zone (0-5) the truck is in and determine the best course of action. This feature is especially helpful because technicians can tell at a glance that a forced regen is not required if the truck is in regen zone 0 or 1.
4. Troubleshooting
A technician should not have to guess that a forced regen will correct an issue. By accurately troubleshooting the problem, the solution should become evident.
Using a diagnostic application like JPRO with troubleshooting tasks, technicians better understand what is causing the problem to decide how to fix it.
5. Repair Instructions
After discovering the root cause, detailed repair manuals help guide the technician down the most efficient path to repair the problem.
Noregon’s database of repair information, NextStep Repair, is maintained by ASE-certified master technicians to help technicians of all skill levels follow the correct step-by-step repair procedures. By following these manuals, technicians only force a regen when the instructions require it.
The Costs of Unnecessary Regenerations
There are consequences for running unnecessary regens, all of which affect the cost of ownership and impact a fleet’s bottom line. Technicians and fleets should keep the following points in mind when considering a forced regen.
1. Fuel
Fuel is one of the highest operating costs incurred by fleets. A forced regen tends to burn 1-1.5 gallons of fuel, causing fleets to burn away a valuable resource when the regen is not the solution.
2. Component Stress
A regen causes an engine to sustain substantial revolutions per minute (RPMs) for a considerable amount of time during the process. The heat and undue stress can weaken components and shorten their lifespan, resulting in increased trips to a service center, more parts purchasing, and unnecessary downtime.
3. Increased Repair Times
On average, it takes between thirty and sixty minutes to complete a forced regeneration. The substantial heat required for the regen renders the engine and aftertreatment system untouchable until it has time to cool down.
For these reasons, an unnecessary regen often leads to hours of avoidable downtime before the technician can attempt the next solution. This downtime wastes labor hours and occupies a service bay, affecting downtime on trucks awaiting repairs.
4. Wasted Driver Time
Regardless if the forced regen occurs in the bay or on the side of the road, drivers lose precious time awaiting its completion. Additionally, when the regen doesn’t correct the problem, the driver incurs morel downtime waiting on a tow or mobile repair visit and the associated repair work.
Repeated instances can threaten driver retention rates, and fleets risk lowering their on-time delivery rates.
Summary
At Noregon, we provide diagnostic and repair solutions that help shops and fleets maximize vehicle maintenance efficiency. Explore JPRO diagnostic software and NextStep Repair software to learn more!