If you own equipment powered by a Yanmar diesel engine, you may have encountered regeneration requests on your display or dashboard. Understanding the regeneration process is crucial because proper maintenance regeneration directly impacts equipment performance, longevity, and compliance with emission standards.
What is DPF Regeneration?
Regeneration (or often simply referred to as Regen) is an automated cleaning process where your engine’s diesel particulate filter (DPF) burns accumulated soot at above 250°C, converting harmful particulates into harmless ash. DPFs are devices added to the exhaust system, enabling Yanmar engines to meet stringent EPA Tier 4 emission standards by reducing harmful particulate emissions.
The DPF captures soot particles from your engine’s exhaust, but requires periodic cleaning through regeneration. When your engine operates at sustained high temperatures during heavy-duty work, accumulated soot burns naturally without intervention. However, during lighter loads or lower temperatures, particulate matter accumulates faster than it can burn off, triggering active regeneration cycles.
The Five Levels of Regeneration
Yanmar employs a five-level regeneration system that becomes progressively more intensive:
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- Self-Regeneration (Passive) occurs naturally during regular operation when combustion generates sufficient exhaust heat—completely automatic and undetectable to operators.
- Assist Regeneration automatically activates when additional heat is needed; the electronic controller partially closes the intake throttle to raise exhaust temperatures, allowing you to continue operating the equipment.
Image caption: Assist regeneration allows regeneration to occur without operator intervention. There is no need to stop working.
- Reset Regeneration is automatically activated, triggered by scheduled maintenance intervals (initially 50 hours, then every 100 hours) or when automatic regeneration cannot adequately reduce soot levels. Users typically have an opportunity to postpone the regeneration until a more convenient time or when needed for safety reasons due to the surrounding environment. Due to increased exhaust temperatures, it is recommended to ensure there are no flammable materials near the exhaust.
- Stationary/Parked Regeneration becomes necessary when soot levels continue rising. When required, owners may receive alerts from the equipment, such as caution lights, audible alarms, or diagnostic codes. This process takes 20-40 minutes. (NOTE: See the next section for instructions on how to perform a Stationary Regeneration)
Performing Stationary Regeneration
When the equipment alerts to perform regeneration, typically at 100% soot load. Yanmar recommends taking immediate action to avoid costly, advanced recovery procedures. The four requirements to start regeneration are as follows:
- Move to low-idle speed in a well-ventilated area away from combustible materials, and don’t leave the equipment unattended during the process
- Set your safety interlock to ensure the equipment is stationary. In some equipment, this may mean activating your parking brake.
- Ensure the engine reaches a cooling water temperature of over 60° Celsius.
- Turn inhibit switch off.
Once you have met the requirements, you may activate the regeneration cycle using the designated controls on your equipment. Consult your equipment manual for the controls location. The process should take 20-40 minutes. Once the regeneration light turns off, the operator may return to standard operation of the equipment.
Recovery Regeneration occurs if soot levels continue to rise and stationary regeneration has not been performed. Recovery regeneration is a backup mode that results in the engine derating (reducing power) normal operation until the regeneration has been completed. It is typically activated from the operator station, depending on the equipment manufacturer.
Safety and Cautionary Notes
If you ignore regeneration warnings for more than two hours, the engine may derate (resulting in reduced power), and may also automatically shut off power to any attached equipment. This is a safety and compliance feature that will remain enabled until the required regeneration cycle is complete. This forces owners to address the emissions system maintenance rather than continuing to work, which could cause damage to the engine and create compliance issues.
While regeneration warnings can appear during seemingly inconvenient times, such as during a vital operation or at the end of a shift, the timing is typically based on soot accumulation levels. Factors that accelerate soot buildup include:
- Light-load operation
- Frequent idling
- Short duty cycles that don’t allow the engine to reach full operating temperature
When the soot load reaches a critical threshold (typically 100%), the warning system activates.
When users receive regeneration notifications, they must address them immediately. Waiting can create mechanical problems and be more costly. Don’t cut short regeneration mid-process or ignore the warnings. Follow proper procedures using the correct fuel and oil specifications to prevent premature system failures and minimize downtime. Always consult your equipment manual or authorized Yanmar dealer for model-specific procedures.
Watch Videos on Regeneration
For a visual example of the regeneration process, watch these videos from Yanmar Academy for an overview of regeneration and how to conduct a Reset and Stationary regeneration.
For support or questions, contact Yanmar customer support at yanmarengines.com/contact-us.