i was wondering if the re-gen mode is activated by a timer that goes off after every (x) amount of minutes, or when the dpf says it is dirty

thanks,

Dayton

 

I believe the regen mode is activated by the ECM using exhaust pressure sensors located before and after the DPF. When the pressure variance between the pre-DPF and post-DPF sensors exceeds a certain value (indicating the DPF is becoming full), the ECM triggers a regeneration event to clear the DPF.