DEF Limp Mode

[Gammel]

Trying to learn me up on diesels as one is in my future. I've read a bunch of horror stories of 'DEF Limp Mode'. Now I'm all in favor of helping the birds and the bees (as long as they're not Killer Bees) but designing engines that give you 100 miles to get to a dealer i[ moderator edit]definitely frosts me. I now better understand why guys 'delete' their diesels. Trouble is that I will be buying a new one so I don't want to delete my warranty. I've read about some gizmos you can plug into the computer plug that will reset the puter to enable you to go farther than 100 miles. I like going a lot farther than 100 miles from a dealer and I just know that if I ever get the dreaded 'Limp Mode' display it will be on a Friday afternoon before a 4 day holiday more than 100 miles from a dealer. I also figure that if I bought one of those gizmos the puter would rat me out and void my warranty. What's a guy to do other than hope he lives a charmed life?

A good honest read on DEF from Cummins:
https://www.cumminsfiltration.com/si...es/MB10033.pdf

[R.Wold]

You get about 5000 miles out of a full def tank on a 6.7 Ford. That’s always been enough for me but I still carried a couple jugs when I was towing a 5th wheel because storage was easy and it just made sense.

I still have the jugs, now over three years old and probably not suitable for use any more. But it provided me with a margin for error in the event I couldn’t find DEF (available just about everywhere) or just procrastinated too long.

I now carry it on my DP for the same reasons and again, will probably never need it. But like you, I’m not thrilled with the idea of going in to limp mode.

[jacknife]

Carry a diagnostic scanner . I had that happen to mine . I scanned it showed the code. Cleared it and it never came back . Ghost codes happen .

[NevadaNick]

I have put about 500,000 combined mi in the last 9 years on a few different trucks, 2 dp mh and a suv that use def and have never been in limp mode.

[tuffr2]

I have seen 'DEF fault Limp mode in 50 miles' on an old Gen 1 2012 Ford Superduty diesel that I owned. Lucky I was 15 miles from a Ford garage. The tech fixed it with a laptop. The truck only was 9 months old and most likely a TSB on the problem. No more limp modes for the remaining 6 years of ownership.

Actually zero problems with this truck.

If I ever bought another diesel I would probably run 'Diesel Efficient' fuel because what I have read it gives a tiny bit better mpg but more important reduces the number of re-gens the truck does.

I would think the current diesel engines to be less problematic than 10 years ago.

[cletesingler]

What, me worry....... You have to be a 'lil unusual to not heed the warnings on the Ford, one at 500 miles to go: "500 miles of DEF remaining", one at 250 miles (I think): "250 miles of DEF remaining" and so on and on and on. If you then in the mean time stop 2-3 times at a truck stop to fill up on diesel and ignore the other pump handle called "DEF", well then, I'm not sure what to offer.................

[kdauto]

Originally Posted by Gammel

Trying to learn me up on diesels as one is in my future. I've read a bunch of horror stories of 'DEF Limp Mode'. Now I'm all in favor of helping the birds and the bees (as long as they're not Killer Bees) but designing engines that give you 100 miles to get to a dealer i[ moderator edit]definitely frosts me. I now better understand why guys 'delete' their diesels. Trouble is that I will be buying a new one so I don't want to delete my warranty. I've read about some gizmos you can plug into the computer plug that will reset the puter to enable you to go farther than 100 miles. I like going a lot farther than 100 miles from a dealer and I just know that if I ever get the dreaded 'Limp Mode' display it will be on a Friday afternoon before a 4 day holiday more than 100 miles from a dealer. I also figure that if I bought one of those gizmos the puter would rat me out and void my warranty. What's a guy to do other than hope he lives a charmed life?

A good honest read on DEF from Cummins:
https://www.cumminsfiltration.com/si...es/MB10033.pdf

I would not be hooking any "gizmos" that could disable emissions functions nor would I "delete" any emissions systems. I wouldn't call people enforcing emissions regulations nazis either. Does ANYONE want clean air for their kids and grandkids?

Most times a diesel enters limp mode is not enough "regens" enabled. This will happen if people buy a 450 HP/1000ft-lb diesel monster but use it to buy groceries and shuttle kids to school, or driving very short distances constantly, never working the vehicle nor getting everything up to temp.

Limp mode "can" happen when one or multiple sensors or wiring go bad, but I'd say it's a fraction of the poor driving habits I mentioned.

Most makes will detect if non-OEM software was uploaded at some point, even if the original software gets reloaded. This will effectively allow the OEM to void any warranty repairs on the emissions systems, a very costly gamble.

[Fleagle]

I bought a 2020 Ram 2500 with the diesel. I refuse to let the what If's ruin my life with worry. Yes I will use my truck as designed and use the products it calls for DEF being one of them. I have 1900 miles on my truck and refuse to do any mods or additions based on improving mileage or transmission shifting etc...
I pull a 2020 Flagstaff weighing about 7300 lbs every month or so. The rest of the time I am driving back and forth. Don't beat your self up trying to figure out everything. Enjoy life, it's too short already with out worrying.

[Reevesfamily]

Originally Posted by tuffr2

I have seen 'DEF fault Limp mode in 50 miles' on an old Gen 1 2012 Ford Superduty diesel that I owned. Lucky I was 15 miles from a Ford garage. The tech fixed it with a laptop. The truck only was 9 months old and most likely a TSB on the problem. No more limp modes for the remaining 6 years of ownership.

Actually zero problems with this truck.

If I ever bought another diesel I would probably run 'Diesel Efficient' fuel because what I have read it gives a tiny bit better mpg but more important reduces the number of re-gens the truck does.

I would think the current diesel engines to be less problematic than 10 years ago.

2011 Gen 1 Ford 6.7l. 110k, Stock turbo, injectors. No DEF, No Regen, No codes, No problems. 19 mpg city, 25 mpg Hwy, 14 mpg towing 'da love shack.

[Roam America]

You can get DEF from any Walmart, auto part store or truck stop. No need to go to a dealer for DEF, unless you want to pay more. I’ve even seen it in the auto section of a grocery store.
My truck has a gauge for DEF level next to the fuel gauge. Fill when it’s getting low and avoid messages.

[arcaguy]

Originally Posted by Gammel

Trying to learn me up on diesels as one is in my future. I've read a bunch of horror stories of 'DEF Limp Mode'. Now I'm all in favor of helping the birds and the bees (as long as they're not Killer Bees) but designing engines that give you 100 miles to get to a dealer i[ moderator edit]definitely frosts me. I now better understand why guys 'delete' their diesels. Trouble is that I will be buying a new one so I don't want to delete my warranty. I've read about some gizmos you can plug into the computer plug that will reset the puter to enable you to go farther than 100 miles. I like going a lot farther than 100 miles from a dealer and I just know that if I ever get the dreaded 'Limp Mode' display it will be on a Friday afternoon before a 4 day holiday more than 100 miles from a dealer. I also figure that if I bought one of those gizmos the puter would rat me out and void my warranty. What's a guy to do other than hope he lives a charmed life?

A good honest read on DEF from Cummins:
https://www.cumminsfiltration.com/si...es/MB10033.pdf

I pretty much asked the same question of several friends of mine who are either diesel mechanics or own/drive trucks. To a person they said that the problems come from trucks that are used in the city for short haul deliveries. If you are going cross country in your coach it does not appear to be an issue in general. That said I have heard that some of the International chassis with Cummins engines have had issues with the DEF sensors but I think problem has been fixed. It might be something to check out before you buy.

[Jshopes81]

Last year my work truck gave the limp mode warning. We were half way into a 500 mile trip and the 200 mile notice came up with 1 dealer in the middle. They werent a commercial dealer, but the reflashed the computer about 150 miles out and reset the 200 mi countdown. Thats the only issue ive ever had in a pickuo with def. Big trucks that run 950rpms though, ugh! That stuff causes some headaches.