I am still curious as to how long you can inhibit a regen once it is due, and sent off an email to Kubota,
There is no set amount of time. It's dependent on how the tractor is used, how much the engine is loaded, if it's doing idling or if it's wide open throttle/low load, etc.
There are 5 stages of DPF soot level (SL).
SL1 is no big deal. This typically shows up as you're bush hogging for instance, running at nearly full throttle. The REGEN lamp comes on and stays on solid for a few minutes then goes out. It's important to NOT shut the tractor off or idle down while this lamp is on steadily.
SL2, again not a big deal. Just let it regen when it wants to. You may have to raise the RPM, but the ECU will tell you to with the engine light with an arrow pointing "up".
SL3-now we're getting into possible issues with owners and operators. With soot level 3, you must do what's called a "parked regeneration" (aka parked regen). You'll have to take the tractor away from dry vegetation, set the parking brake, mash the auto RPM button (right button on the L-01 series), let the tractor get up to operating temp, make sure all transmission functions are in neutral. It'll automatically rev the engine and will then reduce speed when regen is complete.
SL4, you MIGHT be able to do a parked regen-but likely will have a code set in the ECU that may have to be cleared by the dealer.
SL5- the DPF will have to be removed and cleaned (or replaced). At this level the engine power is de-rated to I think 50% power, so you won't be able to do much with the tractor. The derating is done to protect the engine. As the DPF gets plugged, it creates a lot of exhaust back pressure and therefore exhaust gas temperature can get really hot, which can melt pistons and damage other components.
With soot levels 2-5 you will get a beep. A soot level 2 will beep slowly. A level 5 will beep quickly. With 4 and 5 you will get a code in the dash and possible reduced engine power. On the M series, a stage 5, the engine will idle-and idle only. I think on the "L" series it'll rev up but won't have any power.
It is obvious when the tractor wants to regen. There's lights in the dash. Then there's the beeper. Don't ignore them unless you like spending money. If you have to replace the DPF, be warned-it's not cheap!
It's a good practice to leave the tractor running when a regen cycle starts. Shutting it off during a regen is a great way to prolong the process; because the engine needs to be at operating temperature in order to regen. So if you shut it down, come back the next day, you'll have to wait for the engine to warm up for it to start the process-which takes a LOT more time than, say, just letting it work. I know people who have done this and I know at least one of them that the regen process has taken months for this exact reason. On this note, it's always a good idea to make sure the radiator and screens are clean. Once regen starts, the engine RPM will be high. Debris in the screen/radiator can cause it to overheat. I don't know how Kubota has worked around this with the ECU regen cycle programming since I haven't dealt with it yet. Just a heads up-keep it clean. An L3301 that overheats and destroys the engine is considered a total loss due to the expense of replacing the engine and DPF. I did an insurance estimate earlier this year for just this isue and the estimate was in the $18,000 neighborhood, BUT this was a worst case scenario.