When driving around town, my truck used to regen when the DPF got between 75%-80%. If I was on the Highway it may wait to 85% but never more. I don’t generally disrupt regens but a month ago I interrupted one in the morning going to work because I was short on time. Since then, my truck now starts to regen at 95%. It takes a LONG time and then stops the regen around 10%. Anybody know why this would change?

 

How do you know if it is in regen? What are the clues you are observing? At what mileage hacks are you seeing the regens? How do you normally use your truck? Have you changed how you use your truck? How much do you understand about the regen process for your truck?

 

Please see above.

 

Mine is a 2018 and the process may be different. On a normal regen cycle, mine will not go into regen until the filter hits 99 percent. There are only two ways I am aware of for the PCM to send the system into regen at 85 percent: One is where you have been passively regening and you reach the 500 miles limit to where the computer puts the system in active regen. It does this regardless of soot load. The second instance would be when the truck started a regen, but then paused because you were no longer in regen parameters, like when you park the truck. It would then pick up the regen at that 85 percent mark. It has been my observation that the system will restart a regen when the regen was interrupted before the system got to 60 percent. I don't know that as an absolute but on two occasions, my truck went back into regen when interrupted at 65 percent. Below that, it won't go back into regen once interrupted.

With all city driving, I'm surprised you go 250 miles between regens. My use is similar. My soot climbs around .6 percent per mile, or around 150 miles between regens if I start at zero. It has been pretty constant there. I only occasionally regen down to zero. Most of the time, it stops between 15 and 30 percent because I'm no longer driving under conditions for the regen to continue. I don't drive the truck for no reason other than to get it to regen to zero.

I'm not much help here since, again, my 2018 could be completely different from the 2021 regarding emission systems. Maybe a newer truck owner can relate their observations.