2025 Cummins Regen Observations

[Brutal_HO]

Not 2025 so nothing to add except anecdotal comments, but nice to see my gauge drop to 0 on a passive not towing drive today. Took the Grandson to an Orthodontist appt about 30 mins each way. Jumped to 12.5% (1/8) half way out, dropped to 0 half way back. 60-65MPH max speeds but mostly slower.

That said, my last 2 regens have been VERY low time/miles - ever since the oil/filters were changed...

 

[Forceofwill]

I'm at just under 800 miles on the truck. Drove it home from DC, 202 miles highway with some medium traffic slow downs. Then been driving it as my daily. Have a 21 mile commute about 15 of which is highway. On the way home I always encounter a lot of stop and go on the way back. It takes me about 45-1hr to get home 21 miles. I've done a few short store and restaurant trips in there too.

I've seen the DPF gauge get as high as about 33%, checked again today and it was back at like 5%. It seems to be doing well passively maintaining for me so far.

 

[gurdbonk]

I'm at just under 800 miles on the truck. Drove it home from DC, 202 miles highway with some medium traffic slow downs. Then been driving it as my daily. Have a 21 mile commute about 15 of which is highway. On the way home I always encounter a lot of stop and go on the way back. It takes me about 45-1hr to get home 21 miles. I've done a few short store and restaurant trips in there too.

I've seen the DPF gauge get as high as about 33%, checked again today and it was back at like 5%. It seems to be doing well passively maintaining for me so far.

Are you sure you didn't get an active regen on the way home? I haven't been able to tell when I am in active regen.

 

[Forceofwill]

Are you sure you didn't get an active regen on the way home? I haven't been able to tell when I am in active regen.

It probably did. I checked and was at 20 drive 4 idle after I posted that. It never gave me a message and I didn't notice a noise. But I noticed my gas mileage was a little worse but didn't think much of it.

 

[Mhub]

In my 2025 2500 Limited the cruise control activation and set button do not seem to be triggering the high idle. Is there a new way to activate high idle for the 25’s??

 

[Xflight29]

In my 2025 2500 Limited the cruise control activation and set button do not seem to be triggering the high idle. Is there a new way to activate high idle for the 25’s??

My 25 3500 I just set cruse and minus at same time.

 

[PyroJoe]

I pulled up every EGT gauge there is at once on the CTS3. 11 & 12 read the hottest when not in regen. It actually stands for Bank 1 Sensor 1 and Bank 1 Sensor 2. My best guess is 11 is the closest to the manifold. 12 will stay at temperature longer, so if you let off the throttle after a hard pull, 11 will drop quickly, leaving 12 looking like the hotter probe. Not sure why that would be.



The gauge cluster DPF is a joke. It doesn't tell you when in regen. Doesn't tell you the actual percentage (whereas the other gauges will show you the actual number). And compared to the CTS3, the little bar graph isn't even accurate! It seems that when the CTS3 reads 100% full, the gauge cluster only reads 50% full.
In this pic, the CTS3 shows 46% full.

 

[AH64ID]

I pulled up every EGT gauge there is at once on the CTS3. 11 & 12 read the hottest when not in regen. It actually stands for Bank 1 Sensor 1 and Bank 1 Sensor 2. My best guess is 11 is the closest to the manifold. 12 will stay at temperature longer, so if you let off the throttle after a hard pull, 11 will drop quickly, leaving 12 looking like the hotter probe. Not sure why that would be.

View attachment 88325

The gauge cluster DPF is a joke. It doesn't tell you when in regen. Doesn't tell you the actual percentage (whereas the other gauges will show you the actual number). And compared to the CTS3, the little bar graph isn't even accurate! It seems that when the CTS3 reads 100% full, the gauge cluster only reads 50% full.
In this pic, the CTS3 shows 46% full.


View attachment 88326

The dash DPF gauge isn’t showing you the same thing as the CTS3, that’s why they don’t match.

The dash shows soot loading only, which will trigger a soot based regen at ~45%.

The CTS3 is showing you “regen trigger” and that’s based on the higher of soot loading or 24 hours. Looking at your photos it appears it’s been ~11 hours since your last active regen?

 

[PyroJoe]

The dash DPF gauge isn’t showing you the same thing as the CTS3, that’s why they don’t match.

The dash shows soot loading only, which will trigger a soot based regen at ~45%.

The CTS3 is showing you “regen trigger” and that’s based on the higher of soot loading or 24 hours. Looking at your photos it appears it’s been ~11 hours since your last active regen?

Its been about 1 hour or less since regen. I just completed a 2600 mile trip. Had lots of regens.

 

[AH64ID]

Its been about 1 hour or less since regen. I just completed a 2600 mile trip. Had lots of regens.

Not abnormal to see 46% on the CTS3 even after that. What I found is that the first 12 hours after a regen the PID is driven by soot and moves around a lot between ~25-45%. That’s because the soot loading bounces a lot, then after 12 hours the timer runs that PID and it stops bouncing and slowly ticks up to 100% and a regen happens. Thats assuming good driving that promotes 24 hour regens.

After an active regen finishes drive for a couple minute to let the truck cool, then shut it down for 5-10 minutes. When you turn the truck back on the % on the CTS3 will show you residual soot. I’ve seen as low as 0.00% after a 24 hour regen with 6400 in the tank and as high as the 20’s after a soot based regen.


All that’s from the 22, so there may be some differences on how the PID reports for the 25, but it sounds similar at this point.

 

[PyroJoe]

I never said 46 was abnormal. That regen got cut short. I've noticed once you put it in park, that shuts the regen off. If the trigger % is below a certain number, it considers the process complete and doesn't go back into regen the next time you put it in drive. I don't remember exactly what the number was. I think 45% was the threshold. Might be 35.

If you just keep driving while in regen though, it'll go to 0.

It really sucks we can't force a manual regen. I'd have loved to gotten the regen done before I hit the big mountain grades on my trip. Sure enough, it started the regen right before Eisenhower pass and right before I got home. I wasn't going to sit around when I got back, being exhausted from 37 hrs of driving in 3 days. It'd also be nice if we could let it regen when parked like the C&C can.

 

[AH64ID]

I never said 46 was abnormal. That regen got cut short. I've noticed once you put it in park, that shuts the regen off. If the trigger % is below a certain number, it considers the process complete and doesn't go back into regen the next time you put it in drive. I don't remember exactly what the number was. I think 45% was the threshold. Might be 35.

If you just keep driving while in regen though, it'll go to 0.

It really sucks we can't force a manual regen. I'd have loved to gotten the regen done before I hit the big mountain grades on my trip. Sure enough, it started the regen right before Eisenhower pass and right before I got home. I wasn't going to sit around when I got back, being exhausted from 37 hrs of driving in 3 days. It'd also be nice if we could let it regen when parked like the C&C can.

I was just referencing where you said the dash was a joke and not accurate. It’s accurate, just a totally different scale.

35% is the point on my 22 where a soot based regen wouldn’t retrigger (which honestly I think is a huge programs mistake and cause additional problems). I don’t recall any time based regens not restarting after a shutdown.

 

[PyroJoe]

I don’t recall any time based regens not restarting after a shutdown.

That sounds to be the same for 2025's. I've had what I believe was the time-based regen, which would start IMMEDIATELY after starting the truck. It blows my mind they don't even let the truck warm up fist. I only had the OBDLink MX+ at that point, which shows a 0 or 1 for regen status. I'd start the truck, it'd change to 1 and go into an elevated idle. If I put my foot on the brake, it'd idle back down and pause. I started the truck 6 or 7 times during this process as I was outfitting & detailing the truck and moving in & out of the shop, and it did it every time.

 

[AH64ID]

That sounds to be the same for 2025's. I've had what I believe was the time-based regen, which would start IMMEDIATELY after starting the truck. It blows my mind they don't even let the truck warm up fist. I only had the OBDLink MX+ at that point, which shows a 0 or 1 for regen status. I'd start the truck, it'd change to 1 and go into an elevated idle. If I put my foot on the brake, it'd idle back down and pause. I started the truck 6 or 7 times during this process as I was outfitting & detailing the truck and moving in & out of the shop, and it did it every time.

I too was surprised that the truck would indicate a regen on a cold engine, but it never did anything to regen until it warmed up. There needed. to be a certain EGT and ECT for fuel to be injected. The 25’s with the 7th injector might just need a certain EGT as cylinder washdown isn’t an issue for regen.

 

[Xflight29]

I must ask, what is the concern over regen? seems like it is doing what it is supposed to do. I just drive my [25] 3500 and not even worry about it. Could it be possible this is how it was designed? How does anyone know what the engineers, other than the engineers have it dialed in to. Just seems like there is so much chatter about it, just carious.

 

[scdo]

Regens are normal but excessive regens are not. On my 23, I was getting regens every 100-150 miles (with the check engine light coming on frequently). On pre 25 trucks, that can lead to fuel dilution and be a major issue. My 25 has been flawless in this regard, only ever triggering a regen at 24 hours.

 

[AH64ID]

I must ask, what is the concern over regen? seems like it is doing what it is supposed to do. I just drive my [25] 3500 and not even worry about it. Could it be possible this is how it was designed? How does anyone know what the engineers, other than the engineers have it dialed in to. Just seems like there is so much chatter about it, just carious.

I’d they worked as designed then yes, nothing to worry about. CGI regens, especially around 2022, did not work as designed so a lot of attention has been paid to them. It remains to be seen if the issue was fixed for 2025 or not.

It’s really frustrating when 13-18 trucks worked nearly perfectly for regens.

 

[PyroJoe]

My biggest gripe is the fact they don't tell us we're in a regen while the 1500's do and Ford does (not sure on GM), and all other equipment we own with DPF's do. It's a fire safety hazard when it gets that hot. And as I've mentioned several times, the last thing I want to do when it's in a regen is shut if off like normal. At the very least, I want to give it an extended cool down time for EGT's sake.

 

[PyroJoe]

Would the CTS3 not indicate that I'm in regen? There's 2 types of regen, right? I'm sitting parked, in D with my foot on the brake, and the EGT's are trying to climb to 800°. If I put it in park, they drop. I've started making a habit of trying to let it cool to 440° before pulling in the garage. The other indication was I couldn't get instant mpg above 17mpg. Normally I can hit 21 when trying. But it absolutely wouldn't go above 17 on my drive home.

Also, you can see my average distance and time between regens on the right side of the gauge.

 

[AH64ID]

Would the CTS3 not indicate that I'm in regen? There's 2 types of regen, right? I'm sitting parked, in D with my foot on the brake, and the EGT's are trying to climb to 800°. If I put it in park, they drop. I've started making a habit of trying to let it cool to 440° before pulling in the garage. The other indication was I couldn't get instant mpg above 17mpg. Normally I can hit 21 when trying. But it absolutely wouldn't go above 17 on my drive home.

Also, you can see my average distance and time between regens on the right side of the gauge.

View attachment 88608

Active regen should show but passive regen won’t.

Time and distance between regens was never accurate on my 22, maybe it’s fixed for 25 but neither of those numbers are good. Less than 8 hours average between regens on a new truck is bad.

That doesn’t seem like a regen (based on PIDs and typical regen behavior), but rather something dragging the engine down in gear. What was your engine load? Trans driving and shifting normal?