I have a L3901; by mistake I interrupted the regeneration cycle (parked in neutral) to go to a meeting. When I start it now it beeps, and the only light on is the red one on the right of the instrument panel. The manual says that I should stop immediately and go to my dealer.
I want to check if it has the auto regenerate button. If so, just press the button when starting the tractor. If this tractor only has the inhibit / cancel buttons, then you will not have to press anything because the regeneration will be activated automatically. The tractor only indicates that it has to regenerate. The tractor will need to be at temperature, so I would recommend starting the tractor, letting it idle at 1000rpm and letting it run for 20 minutes to half an hour to get the engine temperature.
The regeneration cycles in these engines are all automatic, so it only needs the heat and it will do a park regeneration if you leave it in the park. You want to see if the tractor revs rise on its own, or the light on the dash indicates that it is doing a regeneration. RPM should take 20-30 minutes, so if the tractor does not regenerate and stops with 2 hours of operation, then there is something wrong. Don’t worry about doing any harm because the machine is computerized enough to know that it will shut down if there is a threat of harm. The machine only needs to get hot enough to regenerate and finish it and there should be no problem once it completes the cycle.