I am manual regeneration about every 100 miles of normal running about 60-65 mph but less if running at higher speeds I had burner updates less then 75,000 miles since nozzles replaced ignitors replaced was regenerating on auto but now manual the last two trips I manual regen and 2 hours later it auto regen on its own I'm getting P141F codes powertrain, MFG, Auxiliary Emissions Control, Fault:1F about a couple months ago somebody stole my DEF fuel tank top it was about a month or so be I found a new one but I plug the fill top relatively secure but we had some rain afterwards would water in the tank affect the operation of the unit the tank was on half and I filled with a new box of DEF fuel