There are two types of regen.
- Passive regen. This occurs during normal operation of the machine IF the machine is being worked hard enough to get the exhaust hot enough. If the machine is not worked hard enough for passive regen to occur, then active regen must take place.
- Active regen. For this to happen either the operator must run the machine with the throttle dial in the upper range for a period of time, or the machine must be parked for the active regen to be carried out automatically. The exhaust temperature is raised by altering the fuel injection timing. If the operator doesn't allow active regen to take place, after a series of warnings, the engine will start to derate. If active regen STILL isn't allowed to occur, the engine will derate to almost idle and ET will be required to carry out the regen. Note also that active regen won't happen if the engine has any active fault codes present.
The regen process burns the soot from the DPF. The DPF then collects the ash. The ash loading is calculated by the ECM based on time, fuel used and other variables. 3000 hours is the time limit recommended to either clean or replace the DPF. Nothing will happen if it isn't replaced at 3000 hours except the ash load will continue to increase. As the calculated ash load increases, active regen will occur more often. If the ash load gets to the point where regen is occuring more than every half-hour, error codes will be logged.
When the DPF is either cleaned or replaced, ET must be used to reset the ash loading.
Information in SIS on the emissions system is pretty fragmented and the above is based both on this and my own first hand experience. It applies only to D series skid steers with the Tier 4 interim Kubota engines. (Non SCR emissions systems, that is, engines that don't use DEF)