The Diesel Particulate Filter (DPF) trap the particulate matter before it can be exhausted.
Once the honeycomb filter captures enough particulate matter, flow becomes restricted.
Regeneration is the process of cleaning out the filter.
Note: Operator initiated regen only applies to Perkins 854 and Caterpillar 3.4B engines. For other model engines, operator regen input is not required, and not possible.