Diesel noob. Sorry In advance. Def question.

[Schwingel9]

The truck has 700 miles on it now maybe 20 miles towing, the rest highway and minimal idle. The def gauge is still at 100%. Is this normal or could someone in the gauge system be faulty? Any idea after how many miles should it move at least a little bit? I did read the previous threads but they seem mostly concerned with excessive usage. Thanks!


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[Rockcrawlindude]

I believe normal Def usage is in the neighborhood of 2-3% of diesel usage

If that’s true and if you get ~16mpg and have driven ~700 miles then, in theory, you should’ve used ~ .8 gallons def

 

[RV_Goose]

I believe normal Def usage is in the neighborhood of 2-3% of diesel usage

If that’s true and if you get ~16mpg and have driven ~700 miles then, in theory, you should’ve used ~ .8 gallons def

The DEF guages on my 2013 2500 and my 2020 3500 show full until w gallins is gone. It's not linear reflection on the DEF guage. At 1/2 reading on the DEF guage, I barely can empty a 2.5 gallon def container. So I basically over fill it to empty the DEF container.

 

[Schwingel9]

I think it actually just moved, slightly. Thanks!


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[Sir Snacksalot]

Filled mine at ~10 miles on truck. Didn’t add a 2.5 gallon container until about 2500 miles on the truck. No need to worry it will move


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[Schwingel9]

Thanks!


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[CDNgoat]

read somewhere on here not to fill them completely full , will go into limp mode for some reason, I wouldn,t worry about the guage, who knows if its even accurate, pretty sure the truck will let you know when it gets low , when DEF first came out there weren,t any gauges it was a guess and a mess, just be thankfull Ram has sort of figured out the DEF toilet seat ride. could be a ford when they go into regen they look like their on fire and I had a 2016 duramax used mostly in the city and it be in regen mode for days, its not us little pions causing global warming ,its big industry but we will pay for it

 

[jeffn]

lucky… I just towed a modest 10k lb enclosed trailer 3k miles and used 10 gallons of DEF

 

[RV_Goose]

lucky… I just towed a modest 10k lb enclosed trailer 3k miles and used 10 gallons of DEF

The 10 gallons is 300 miles per gallon, which is average. What was your fuel mileage?

 

[jeffn]

The 10 gallons is 300 miles per gallon, which is average. What was your fuel mileage?

9.6

 

[raven_dt]

The truck has 700 miles on it now maybe 20 miles towing, the rest highway and minimal idle. The def gauge is still at 100%. Is this normal or could someone in the gauge system be faulty? Any idea after how many miles should it move at least a little bit? I did read the previous threads but they seem mostly concerned with excessive usage. Thanks!


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Make sure that you check the manufacture date on your def. Don't buy stale DEF.

 

[MrTaz]

The truck has 700 miles on it now maybe 20 miles towing, the rest highway and minimal idle. The def gauge is still at 100%. Is this normal or could someone in the gauge system be faulty? Any idea after how many miles should it move at least a little bit? I did read the previous threads but they seem mostly concerned with excessive usage. Thanks!


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I usually average about 4000 miles on a tank when not towing but city driving can affect it too.

 

[gimmie11s]

read somewhere on here not to fill them completely full , will go into limp mode for some reason,

lol what?? No.

lucky… I just towed a modest 10k lb enclosed trailer 3k miles and used 10 gallons of DEF

9.6

Sounds right. We did a 2500 mile trip to Yellowstone towing ~12k lbs and i averaged just over 9mpg.. however, we were never under 70mph on the highway; much of the time actually closer to 80mph (yeah, yeah, i know).

Truck was burning through DEF like a god damned drunken sailor.

1075 lb/ft torque does have a cost!

 

[Will_T]

read somewhere on here not to fill them completely full , will go into limp mode for some reason,

I saw that thread too. May be this one? Supposedly overfilling is what causes the problem but I am not sure how accurate that is. I have determined that when my DEF gauge shows 1/2 full a 2-1/2 gallon container will fill it. So I wait until the gauge is just under 1/2 and empty in a box. That way I know I am not getting DEF all the way up the filler neck/tube.

 

[Moparman1230]

I saw that thread too. May be this one? Supposedly overfilling is what causes the problem but I am not sure how accurate that is. I have determined that when my DEF gauge shows 1/2 full a 2-1/2 gallon container will fill it. So I wait until the gauge is just under 1/2 and empty in a box. That way I know I am not getting DEF all the way up the filler neck/tube.

Yep. I do the same thing. That also keeps me from having to store partial jugs.

 

[Lary0071]

Does the Ram DEF tank heaters run when the truck is off as well as running? I had read a TSB that was posted saying that DEF can freeze and if we fill the tank we could see freezing that would split the tank and not be a warranted item. My buddy at work claims that his GMC DEF tank heats even when the truck is off, he hears the solenoid click once in a while in the driveway during winter.

 

[MrTaz]

Yep. I do the same thing. That also keeps me from having to store partial jugs.

To avoid partial jugs I fill my DEF tank at the local truck stop. It’s about 50% cheaper than boxed DEF and since it’s a truck stop the DEF is more likely to be fresh. It’s the only thing I buy at a truck stop. I won’t buy their over priced bio-diesel fuel that requires shorter maintenance intervals.

 

[jeffn]

To avoid partial jugs I fill my DEF tank at the local truck stop. It’s about 50% cheaper than boxed DEF and since it’s a truck stop the DEF is more likely to be fresh. It’s the only thing I buy at a truck stop. I won’t buy their over priced bio-diesel fuel that requires shorter maintenance intervals.

how do you end up with partial containers? If you fill when the gauge is below 1/2 it will take a full 2.5 gallon container. I’m pretty OCD myself but there is no prize for keeping the DEF full.

There is a runnung debate about topping off vs running to the light. The manual says don’t top off the DEF. I don’t know, given how quickly I run through DEF I would say a bad container is more likely than going bad in the tank. I fill when it goes below 1/2 unless I‘m doing a long trip and then I wait until I see the light and then the super-warning message. Then I fill at the pump and save the hassle with the containers.