DEF consumption weirdness
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Posting Guru
Joined: Aug 2004
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From: Upstate, NY
DEF consumption weirdness
At 6700 miles my truck indicated that the DEF tank had about 600 miles left so I bought 2.5 gallons and dumped it in (Blue DEF) Last week I drove to MD to get the new fiver and on the way back I got a similar indicator that DEF was low. Truck has about 7100 miles on it. I bought another 1.5 gallon jug and dumped it in.
Seems pretty weird that it would use less than 5 gallons in 6700 miles and then use a few gallons in 400 miles, no?
Anyway...got 12+ MPG towing the new fiver home (Cougar 293SAB) at 65 or so. More power than I can use and comfy.... gotta love these trucks.
Seems pretty weird that it would use less than 5 gallons in 6700 miles and then use a few gallons in 400 miles, no?
Anyway...got 12+ MPG towing the new fiver home (Cougar 293SAB) at 65 or so. More power than I can use and comfy.... gotta love these trucks.
More Turbo
Joined: Feb 2009
Posts: 635
Likes: 13
From: Mt. Salem, NJ
At 6700 miles my truck indicated that the DEF tank had about 600 miles left so I bought 2.5 gallons and dumped it in (Blue DEF) Last week I drove to MD to get the new fiver and on the way back I got a similar indicator that DEF was low. Truck has about 7100 miles on it. I bought another 1.5 gallon jug and dumped it in.
Seems pretty weird that it would use less than 5 gallons in 6700 miles and then use a few gallons in 400 miles, no?
Anyway...got 12+ MPG towing the new fiver home (Cougar 293SAB) at 65 or so. More power than I can use and comfy.... gotta love these trucks.
Seems pretty weird that it would use less than 5 gallons in 6700 miles and then use a few gallons in 400 miles, no?
Anyway...got 12+ MPG towing the new fiver home (Cougar 293SAB) at 65 or so. More power than I can use and comfy.... gotta love these trucks.
Fleet Mechanic
Joined: Mar 2012
Posts: 1,738
Likes: 7
From: Land of the Free
i thought for sure when i took delivery of my truck i had a full DEF tank. but now i realize there is no way to know as the DEF indication is sort of an idiot light (DEF OK). so when i did my new engine 1000 mile oil change i filled the DEF tank as well. took 2 gals. which tells me it prolly wasnt full to begin with.
Post Fiend
Joined: Jan 2009
Posts: 6,521
Likes: 11
From: Greenwood, SC
DEF usage is directly related to engine load, fuel consumption, and exhaust gas temp. I suppose you could nail it down to one thing, engine load. Ambient air temp has something to do with it too.
So, if you want to use a lot of DEF, pull the most wind resistant trailer you can find at 75MPH. It's all about NOx. Lots of NOx is made when the engine is working hard, so more def is required to reduce/remove NOx.
So, if you want to use a lot of DEF, pull the most wind resistant trailer you can find at 75MPH. It's all about NOx. Lots of NOx is made when the engine is working hard, so more def is required to reduce/remove NOx.
Thread Starter
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Posting Guru
Joined: Aug 2004
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From: Upstate, NY
DEF usage is directly related to engine load, fuel consumption, and exhaust gas temp. I suppose you could nail it down to one thing, engine load. Ambient air temp has something to do with it too.
So, if you want to use a lot of DEF, pull the most wind resistant trailer you can find at 75MPH. It's all about NOx. Lots of NOx is made when the engine is working hard, so more def is required to reduce/remove NOx.
So, if you want to use a lot of DEF, pull the most wind resistant trailer you can find at 75MPH. It's all about NOx. Lots of NOx is made when the engine is working hard, so more def is required to reduce/remove NOx.
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Lead Driver
Joined: Nov 2011
Posts: 9,544
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Your def tank only has a couple sensors to tell the def level. Fill it right up so it reads full and see how long it takes to burn the tank.
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Lead Driver
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600 MTE is low.
My guess is the 2.5 gallons didn't trip the full sensor.
I fill with 2.5 gallons when I see DEF under half message.
I've never had the 800 MTE message appear.
Did you run a system report after it stopped counting down?
I'm curious if it reported under half or DEF OK.
My guess is the 2.5 gallons didn't trip the full sensor.
I fill with 2.5 gallons when I see DEF under half message.
I've never had the 800 MTE message appear.
Did you run a system report after it stopped counting down?
I'm curious if it reported under half or DEF OK.
Thread Starter
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Posting Guru
Joined: Aug 2004
Posts: 2,402
Likes: 0
From: Upstate, NY
600 MTE is low.
My guess is the 2.5 gallons didn't trip the full sensor.
I fill with 2.5 gallons when I see DEF under half message.
I've never had the 800 MTE message appear.
Did you run a system report after it stopped counting down?
I'm curious if it reported under half or DEF OK.
My guess is the 2.5 gallons didn't trip the full sensor.
I fill with 2.5 gallons when I see DEF under half message.
I've never had the 800 MTE message appear.
Did you run a system report after it stopped counting down?
I'm curious if it reported under half or DEF OK.
Who knows....weird to be sure.
Posting Guru
Joined: Nov 2011
Posts: 2,131
Likes: 0
From: Ararat, VA
I had the same issue. 5300 miles and I got the 800 MTE message. Drove about another 150 miles and added 2.5 gallons. 300 miles later, 800 MTE again. Drove about another 150 miles and added another 2.5 gallons. I've driven about another 500 miles since then, display still says OK. We'll see how long it lasts. I just wanted to add enough to hold me over to my "paid" oil change and let the dealer fill it up.
Elder User
Joined: Apr 2010
Posts: 754
Likes: 0
Best thing like others said is fill it up, get 5 gal. in there not just till it says ok and see what happens.
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