Diesel regeneration (or “regen”) is a process that automatically burns off accumulated soot in the Diesel Particulate Filter (DPF) by raising exhaust temperatures to around 550°C–625°C (or 1000°F+). This converts harmful particulate matter into a small amount of ash, preventing blockages in your vehicle’s exhaust system.
Types of Regeneration
- Passive Regen: Happens automatically while chipping wood under heavy load when exhaust gets hot enough to burn off soot.
- Active Regen: Triggered by the engine computer when soot builds up; the machine alters fuel injection to raise temperatures, often allowing you to keep working while a dashboard light stays on.
- Parked/Forced Regen: Required if soot levels get too high (usually 85–90%) or if previous regens were interrupted. The machine must stay parked while the computer automatically cycles the engine RPMs.
Automatic Regeneration Explained
What happens: The engine computer will automatically begin the regen process while you are actively working the chipper.
What to do: You will notice a DPF light illuminate and your exhaust temperatures will rise, but you can continue feeding brush without stopping. Do not turn off the machine until the cycle finishes and the light goes out. Interrupting the cycle frequently can lead to engine oil dilution and eventually trigger a warning light.
Manual (Parked) Regeneration Explained
If your DPF becomes too clogged, passive or active regeneration won’t work. In this scenario, your chipper may need a forced (or static/parked) regeneration. This must either be initiated manually via your dashboard controls or triggered by a mechanic using an Automotive Diagnostic Tool.
- Park safely: Move the chipper to a flat, level area free of dry brush, wood chips, leaves, or other flammable debris. The exhaust can reach temperatures up to 1,000° F (537° C).
- Bring to operating temp: Make sure the engine is fully warmed up to its normal operating temperature.
- Initiate the regen: Toggles for parked regens are typically located on the engine display, on the main dash panel. Hold the “Regen” button for 2–3 seconds.
- Wait for cycle to complete: The engine RPMs will automatically increase. The process takes about 30 to 45 minutes. Do not touch the throttle or shut off the machine while the cycle runs.
- Cool down: When the engine RPMs return to a normal idle and the dash lights turn off, let the engine cool down slightly before shutting it off.
A DPF Filter that is too full or not properly functioning threatens both the environment and the machine. The engine can derate when a needed regen does not occur, potentially causing downtime by leaving the chipper 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.
All that to say this article is for basic information and not to be seen as a diagnosis of your machine’s issue or advice on how to fix issues. When in doubt, take it to a qualified technician. Something I am not.
