Typically unit should regen every 50 hours if you are working tractor above 2k rpm. If not you will see flashing ! Symbol in yellow followed by the regen symbol where the tractor will drop in regen Mode. Rpms kick up to 2.5k and the regen will happen when tractor reaches correct temperature. The cycle could last for 10 to 40 minutes or more depending on how full the canister is with soot. If you think you need to run a manual cycle yourself put tractor in neutral and apply parking brake in a safe place. Hold down regen button for 3 seconds and unit will regen once temperature light regen light is on then RPMs will rise to 2-2.5k rpms and unit will continue cycle until all soot is burned out. That is how it should work based on my prior experiences. Others have noted malfunctions where as the tractor never finishes regen I have not had that issue.