D.e.f question
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Tuned
Joined: May 2011
Posts: 280
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D.e.f question
My 2012 needed topped off at oil change. My buddy got a 2015 dually, we changed oil less than 1000 miles ago. Topped his def off at that time. On his trip this weekend his got the 500 mile message to refill. Did something change in the years between. He is towing a fifth wheel toy hauler. Does towing use more def?
Lead Driver
Joined: Nov 2005
Posts: 5,239
Likes: 4,255
From: Kaysville Utah
The computers will feed DEF in as the exhaust system needs it. DEF is used to reduce NOx which is produced during high combustion temps. So anything that pushed your combustion temps higher, Will consume more DEF.
So if you are idling around with very low temps in the combustion you will not use hardly any DEF. If you are accelerating hard, Climbing grades, or towing you will
So if you are idling around with very low temps in the combustion you will not use hardly any DEF. If you are accelerating hard, Climbing grades, or towing you will
Laughing Gas
Joined: Jul 2010
Posts: 1,155
Likes: 31
From: Idaho
Def
The computer needs to see that DEF level is going down before filling. Don't top of the DEF until the computer recognize that it is low. Now saying that, I fill between less then one half a tank and 800 miles warning. Also over filling DEF in cold areas is a problem, with freezing and expansion. I have never had a DEF issue.
Sometimes computer takes time to see the new level of DEF. The dealer can reset the computer to recognize the new level.
Sometimes computer takes time to see the new level of DEF. The dealer can reset the computer to recognize the new level.
Senior User
Joined: Aug 2015
Posts: 144
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I have not had an issue. But from reading posts on this forum it is obvious to me, do not fill your DEF tank until the computer gives you the less than 50% message. I told a friend of mine that got a 6.7 to wait until after it is below half. Carry a 2.5 gal jug of it just in case you get too low.
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Senior User
Joined: Jan 2013
Posts: 238
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From: Northern New Mexico
I have not had an issue. But from reading posts on this forum it is obvious to me, do not fill your DEF tank until the computer gives you the less than 50% message. I told a friend of mine that got a 6.7 to wait until after it is below half. Carry a 2.5 gal jug of it just in case you get too low.
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Brett Foote
Senior User
Joined: Aug 2016
Posts: 164
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From: Olympia, WA
I would 2nd this, for me the fuel seems sometimes makes an even bigger difference in DEF consumption than even while towing.
Also, I have used B20 a number of times, and I see my DEF consumption go way up when using it. Once made the the mistake of filling up with B20 while I was towing, ate through 2.5 gallons in only 1000 miles.
Also, I have used B20 a number of times, and I see my DEF consumption go way up when using it. Once made the the mistake of filling up with B20 while I was towing, ate through 2.5 gallons in only 1000 miles.
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cstanley44
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Jun 26, 2012 02:02 PM