DEF going away ?

[Shawn T. W.]

But "my lane" is actually in the industry as a tier one supplier, closely partnered with the OEMs producing internal combustion engines for the CTOHI industry. My employer manufactures a wide variety of engine components, sells to nearly every engine manufacturer, and I manage our engine dynamometer lab to test all of it. So I am deeply integrated within the industry that relies on and sells this emissions compliance technology in all of their engines/vehicles.

I can tell you this: none of the OEMs are talking about warranty concerns, problematic DPF/SCR systems, or anything like that. There were a lot of teething problems 10 years ago, sure. But the broad industry perception is that this is a solved issue.

Maybe you should try a brand new truck instead of driving all those old beaters with early emissions compliance systems.

I'm not bashful and will share my experience with pictures ...

I'm not @Hay Dude , but I drive what most here would consider a "brand new" truck .. or at least it was when our company representative picked it up at the Kenworth plant in Chillicothe, OH, and drove it to our headquarters to get processed into our fleet ... I picked it up at 327 miles on the odometer this spring on May 2, 2025 ... Here it is just today ... A 2026 T680 with a Cummins X15.

This picture is also just taken ... The check engine light is on for the second time! While is probably "only a $100 sensor" it means down time for me, time I can't be taking care of a customer, plus the shop time ...

Here are the stickers in the door jamb ...

And the engine ...

And the transmission can certainly effect the engine!

I have the PACCAR 12 speed automatic transmission (worst thing I've ever driven in over 33 years of driving a truck!!!)

Between the programming of the engine and the transmission it doesn't really allow the engine to "work" in my opinion, it double shifts (skip shifting ) and lugs the engine down ... You can see where this redlines, and at the governed speed of 68 mph, it's just barely over 1200 RPM ... It's just lollygagging along, diesels, especially modern emissions diesels need to work hard to run efficiently, so for all the money they "save" in so called fuel economy, I generally get "mid 8's" ... They more than make up for it extra maintenance and headaches expenditures!

This is not an old beater, by any standard, although I hate driving it! But it is a strangled, compromised truck!!!

 

[EscapedSuburbia]

I can tell you this: none of the OEMs are talking about warranty concerns, problematic DPF/SCR systems, or anything like that. There were a lot of teething problems 10 years ago, sure. But the broad industry perception is that this is a solved issue.

I have no experience in the heavy truck world but do in the diesel pusher RV world and the DEF failures have definitely not been solved. Improved, but not solved. DEF head failures are still a very common complaint in new RVs.

 

[Hay Dude]

I don’t think much anyone’s buyin what deezler’s sellin

 

[dnw64]

I don’t think much anyone’s buyin what deezler’s sellin

Some people are their own best customer.

 

[deezler]

Lol. I appreciate the anecdotal pieces of evidence.

Was just trying to share the perception from the engineering side...

The engines are all robust, at this point. The Cummins X15 hasn't changed much in years - It does just fine loping along at 1200rpm low load, indefinitely. The challenge comes when you need to integrate a comprehensive exhaust aftertreatment system onto it.

For what its worth, I feel like I am noticing a pattern with Paccar and DPF/DEF/SCR issues. The aftertreatment system isn't always engineered or integrated by the engine manufacturer (which is dumb).

 

[deezler]

I'm not bashful and will share my experience with pictures ...

I'm not @Hay Dude , but I drive what most here would consider a "brand new" truck .. or at least it was when our company representative picked it up at the Kenworth plant in Chillicothe, OH, and drove it to our headquarters to get processed into our fleet ... I picked it up at 327 miles on the odometer this spring on May 2, 2025 ... Here it is just today ... A 2026 T680 with a Cummins X15.

This picture is also just taken ... The check engine light is on for the second time! While is probably "only a $100 sensor" it means down time for me, time I can't be taking care of a customer, plus the shop time ...

View attachment 4562188

And the transmission can certainly effect the engine!

I have the PACCAR 12 speed automatic transmission (worst thing I've ever driven in over 33 years of driving a truck!!!)

Between the programming of the engine and the transmission it doesn't really allow the engine to "work" in my opinion, it double shifts (skip shifting ) and lugs the engine down ... You can see where this redlines, and at the governed speed of 68 mph, it's just barely over 1200 RPM ... It's just lollygagging along, diesels, especially modern emissions diesels need to work hard to run efficiently, so for all the money they "save" in so called fuel economy, I generally get "mid 8's" ... They more than make up for it extra maintenance and headaches expenditures!

This is not an old beater, by any standard, although I hate driving it! But it is a strangled, compromised truck!!!

Just because I am curious, and to clarify....

You say "2nd time" the CEL is on, at 94k miles? Thats not particularly awful, is it? What is the CEL actually for? No reason to bash the aftertreatment system that is keeping our air clean if you don't even know what the CEL is on for. Your dash lists and error in the lane departure system....

And yes, the transmission affects the engine, but my point was that a having transmission faults, error codes or mechanical issues does not imply that it is wrong or even at all associated to have a DPF and SCR system in the exhaust keeping our air clean.

And sorry that your employer bought the wimpiest version of the X15, haha. Lot more fun to have the 600HP version, I'd imagine.

 

[Hay Dude]

Lol. I appreciate the anecdotal pieces of evidence.

Was just trying to share the perception from the engineering side...

The engines are all robust, at this point. The Cummins X15 hasn't changed much in years - It does just fine loping along at 1200rpm low load, indefinitely. The challenge comes when you need to integrate a comprehensive exhaust aftertreatment system onto it.

For what its worth, I feel like I am noticing a pattern with Paccar and DPF/DEF/SCR issues. The aftertreatment system isn't always engineered or integrated by the engine manufacturer (which is dumb).

Yes the engines are robust.

But that’s not what you said. You said the emissions systems were “robust and reliable”.

But they aren’t. That’s why one of mine was turned off by the previous owner. We have crops to make. Spending time with a laptop & sensor replacement hinders that process too much.

 

[Hay Dude]

Just because I am curious, and to clarify....

You say "2nd time" the CEL is on, at 94k miles? Thats not particularly awful, is it? What is the CEL actually for? No reason to bash the aftertreatment system that is keeping our air clean if you don't even know what the CEL is on for. Your dash lists and error in the lane departure system....

And yes, the transmission affects the engine, but my point was that a having transmission faults, error codes or mechanical issues does not imply that it is wrong or even at all associated to have a DPF and SCR system in the exhaust keeping our air clean.

And sorry that your employer bought the wimpiest version of the X15, haha. Lot more fun to have the 600HP version, I'd imagine.

600HP diesel engines are great….especially when diesel fuel is $4.39 a gallon
Easy to see you don’t own a business…

 

[Shawn T. W.]

Just because I am curious, and to clarify....

You say "2nd time" the CEL is on, at 94k miles? Thats not particularly awful, is it? What is the CEL actually for? No reason to bash the aftertreatment system that is keeping our air clean if you don't even know what the CEL is on for. Your dash lists and error in the lane departure system....

And yes, the transmission affects the engine, but my point was that a having transmission faults, error codes or mechanical issues does not imply that it is wrong or even at all associated to have a DPF and SCR system in the exhaust keeping our air clean.

And sorry that your employer bought the wimpiest version of the X15, haha. Lot more fun to have the 600HP version, I'd imagine.

The CEL is directly tied to the emissions system, if it was low on coolant or oil or another problem, it would have its own alarm and light, it has lots of lights, and buzzers! The one mostly covered up with black tape is for the high beams, it's too bright in my eyes, so I covered up about 90% of it ...

The lane departure fault came on at about 15K, I wrote it up 3 separate times, it hasn't been fixed, I gave up, as I really don't like it, because it's WRONG more than it's right, so it's kinda like a night light, as I also usually have most of that covered up in black tape too! It has NOTHING TO DO WITH THE CEL!

Yes, my company "cheaped out" we use to run the 455 HP in my 2024 and prior I've driven the 535 HP X15, it's not my checkbook, so I don't have a say in it ... But far from "anecdotal" as I wrote much earlier my company runs about 450 of these trucks, we keep them until 4 years old, or 600K miles, whichever comes first ... AND roughly 75%-80% of all repairs are emissions related, not counting regular pm or tires, A/C is the next most "common problem" ...

Wether the engine is 400 HP or 600 HP, they both Have to meet the same standards, so my little 400 isn't the reason the CEL is on, don't fool yourself that the 600 would not throw a CEL either!

Every single diesel truck I've driven with the emissions systems on them, have ALL given problems ... A freightliner, 2 Internationals, and the rest Kenworth's! Yes, the last few years the problems are not as often, or as bad as 15 years ago, but less than 5 years ago I was down to 5 MPH up hills in WV on I-77 going South trying to get to our shop in Mountain City ... It was going to be much faster service than waiting on KW in Kingsport ...

 

[Shawn T. W.]

Sorry I couldn't show all the warning lights ... Here is most of them from the manual ...

I'm not sure what the CEL is for, I'll call in the morning to see, my shop can look in the computer and see what the problem remotely ... Then decide if it's serious, and start looking for a place to get me in ... When it came on this morning, I was on a hot load to McAllen, TX, now I'm waiting to get loaded in Brownsville ...