DEF ISSUES
Mountain Pass
Joined: Nov 2024
Posts: 183
Likes: 96
Hotter temps don't increase the DEF usage, heavier loads on the engine do that. And don't confuse the DEF usage of the 2023 to that of the 2017 - they are completely different systems that operate differently. Do the late models use more DEF? Yes, but they also burn much more efficiently, so a regen now takes 3-5 minutes where it used to take 15-20 minutes. And my 2023 is better at passively keeping the filter cleaner so regens are even less impactful.
Note the source (Wikipedia).
It’s also a fact that higher load means higher EGT’s, so its true load increases DEF consumption, but the reason is still higher combustion temperature. Interesting you are getting regens in only 3-5 minutes, my 24 has never taken less than 15 minutes - different driving styles, heavy versus light towing maybe?
Mountain Pass
Joined: Jul 2017
Posts: 168
Likes: 11
From: Summit Park, UT
We were getting similar DEF MTE messages on our '25 F450 with around 12k miles on the clock. We didn't have time to take it to Ford so I had our diesel mechanic take a look at it. We filled the DEF tank and he did a reset of the sensor and it mostly solved the problem.
However, even when I let the MTE get to 47 miles and then fill the tank, it only takes about 5 gallons when filled at the pump.
However, even when I let the MTE get to 47 miles and then fill the tank, it only takes about 5 gallons when filled at the pump.
Lead Driver
Joined: Nov 2005
Posts: 5,229
Likes: 4,245
From: Kaysville Utah
The 23+ trucks have a different algorithm than previous gen trucks. They seems to watch the worst DEF consumption and calculate your miles to empty based on that worst consumption.
When I first had my 23, I hauled the horses over Hells Back bone on hiway 12 in Southern Utah. There is a 14% grade on that road.. I dragged the trailer up that grade and my 500 miles to reduced power light came on. I looked at the DEF gauge and it showed 60% left. I drove 300 miles home with the Count down from 500 reducing with each mile. When I got home with 200 mile to reduced power showing, I filled up and it took 3.2 gallons of DEF. So NO, It's not very accurate.
I just top off my DEF tank when ever I have a chance when I buy fuel now. Most stations that are big enough to get a trailer in comfortably have DEF at the pump. Just spend the extra 3 minutes after buying diesel and top off the 2-3 gallons that your DEF needs.
5
When I first had my 23, I hauled the horses over Hells Back bone on hiway 12 in Southern Utah. There is a 14% grade on that road.. I dragged the trailer up that grade and my 500 miles to reduced power light came on. I looked at the DEF gauge and it showed 60% left. I drove 300 miles home with the Count down from 500 reducing with each mile. When I got home with 200 mile to reduced power showing, I filled up and it took 3.2 gallons of DEF. So NO, It's not very accurate.
I just top off my DEF tank when ever I have a chance when I buy fuel now. Most stations that are big enough to get a trailer in comfortably have DEF at the pump. Just spend the extra 3 minutes after buying diesel and top off the 2-3 gallons that your DEF needs.
5
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Mountain Pass
Joined: Sep 2019
Posts: 176
Likes: 58
UPDATE
I have had so many repeat problems with my truck that Ford has agreed to re-purchase it. I was hoping for a way to feel confident keeping it because I love the truck, but I just don't feel that it will last as I had hoped. I worry it is a "monday" truck maybe. SO, I will be ordering a new 2027 maybe.
One note, the last recall I had it in shop for last week was to fix a brake controller issue. I'd been saying since I got this truck new that the controller wasn't working properly. It never threw a code but with the controller cranked up to 9.5 I "just" had trailer brakes. That is NOT normal. I pull horses and have done it enough times to know that something was not right. I hope the recall fixes the issue for good. I haven't pulled my trailer since the fix because IT is in the shop too. Sometimes you can't catch a break but maybe this is the start of better times going forward
One note, the last recall I had it in shop for last week was to fix a brake controller issue. I'd been saying since I got this truck new that the controller wasn't working properly. It never threw a code but with the controller cranked up to 9.5 I "just" had trailer brakes. That is NOT normal. I pull horses and have done it enough times to know that something was not right. I hope the recall fixes the issue for good. I haven't pulled my trailer since the fix because IT is in the shop too. Sometimes you can't catch a break but maybe this is the start of better times going forward
Tuned
Joined: Jul 2010
Posts: 299
Likes: 5
From: Northwestern Ontario
So, are the 2025’s and 26’s experiencing the same DEF issues? I would hope they have this figured out by now. My 2015 has only had one problem with DEF and that was a heater issue. They replaced the tank and all is well. My 2011 was always acting like the issue y’all have described here.
This year, pulling the same 5000 lbs, trailer, on the same route, my new 2026 used 6 jugs of DEF. At one point at the beginning of the trip, I got the 500 mile warning and the gage still showed 50+% full. The message never came up again, and I sometimes ran the DEF down to 25%
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Gordon
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wharrell
2017 - 2022 Super Duty
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Jun 26, 2017 05:04 PM
