The one jug of DEF was down 1.5% and you didn’t use it? I think you have to relax a little. If it’s that critical with these trucks then there’s no point in owning one.
I’m sorry I can’t answer your actual question of when it’s not acceptable to use but certainly not down by 1.5%, and if it is all that takes for limp mode. Well......
Hope you get the official answer.

 

Being mathematically accurate, 31% is 4.6% less less urea than 32.5%: 31%/32.5% = 95.4%. I know that still doesn't sound like much but at some point it makes a difference. And the stuff sits in my truck a while, through hot summers and all. I'd like every bit of margin I can get. I'd also like every bit of urea I paid for. The date code on this jug is nearly new (July 15th). Assuming it left the Peak facility at the proper percentage, how badly was it stored to have degraded this much in 5 days. Or if it left the facility at 31.5%, how hard can it be for them to make the stuff to spec, as affirmed on their label.

 

I think what he was getting at is, if that small of a variance will cripple the truck, anyone running def is doomed. Doooommmmeeedddddd

 

For sure, when it comes down to freeze point, that mixture is probably most important so they’ll end up thawing and freezing at the same time. Otherwise the mixture of percentages would be way off if one becomes a solid or liquid at different times. There’s going to have to be some leeway in there because of this alone.

 

I stand corrected, I found a Cummins service bulletin that states 32.5% +/-1.5% by weight.

Dooooommmmmmeddd

 

And apparently def and the deionized water both freeze at the same rate.

 

No they don’t. That’s why I think the mixture is semi-critical because of this, but since it won’t be a perfect thaw every time there has to be some variance for the injector to compensate for this.
I’m around a lot of ..... that freezes

 

@badunit

Although I cannot confirm, I have read before (here and other sites) that if the DEF quality does drop, the system apparently will inject more DEF to compensate for the reduced quality.

The $64,000 question is.....what ratio of urea does this occur at, which is your original question.

 

That's what the Cummins bulletin said. I'm not cool enough to run def in my truck... but I did read 2 bulletins and stayed at a Holliday in Express last night.

 

Stay one more night. A Cummins bulletin would not be dumb enough to say deionized water has the same freeze point as Urea. There needs to be a mixture there to equal that out.

Get a theme suit and bring the wife.>
Cheers!

 

The truck uses the NOx sensor to determine if the amount of DEF injected is lowering the NOx enough, if not then the system injects more. It doesn't know what the DEF strength is in itself, just the effectiveness of it by the NOx levels. Weaker concentrations of DEF means that more DEF is injected.

But, there is a point of diminishing returns, and this is when the pcm trips a code for DEF quality. When this happens will vary though.

 

A 32.5% solution of DEF will begin to crystallize and freeze at 12 deg F (-11 deg C). At 32.5%, both the urea and water will freeze at the same rate, ensuring that as it thaws, the fluid does not become diluted, or over concentrated. The freezing and unthawing of DEF will not cause degradation of the product.

 

Stay one more night. A Cummins bulletin would not be dumb enough to say deionized water has the same freeze point as Urea. There needs to be a mixture there to equal that out.

Get a theme suit and bring the wife.>
Cheers!

I paraphrased poorly I guess. IronPony copied and pasted what the bulletin said. I actually dont like holiday inns. Hilton hotels are better even if they dont make me smarter.

I also didnt mean to mock. I just throw short jabs for fun.

 

I see me and IP read the same bulletin.

 

Since I have C&C and the DEF filler has a large opening at a convenient height, I know exactly what I'd do if I found out that the DEF was 1.5 % low on urea.

 

No doubt you’re always primed and ready Jimmy.:grin2:

 

Answers are helpful, attitude and mocking are not. The answers so far say I'll be pouring this jug into the tank. It will just use a slight amount more DEF to accomplish its job. I won't be in freezing temperatures.

I am still wondering, though, at what point is it bad enough to cause a fault in the truck.

 

Answers are helpful, attitude and mocking are not. The answers so far say I'll be pouring this jug into the tank.

I am still wondering, though, how the truck detects good DEF from bad and at what point it causes a fault?

Hey don’t take things personal everyone has a bit of fun but still mean well and sorry if you took it another way.

Probably when the DEF injector cannot keep up to see the results it’s looking for at the other end of the SCR may trigger the fault.

 

Here is the Cummins Bulletin referencing DEF standard and requirements. I drain my DEF tank when it gets down to the red. When I put in new DEF it is all fresh. Draining the tank pulls out any old DEF and any sediment. Overkill.....???? Perhaps. A refractometer is your best friend. DEF should be 32.5% Urea. Cummins allows plus or minus 1.5% before the codes and lights start coming up.

 

Hmmmmmmmm.............my DEF doesn’t freeze!!!!!!!!!!! LOL

 

water

i move 5th wheel trailers nation wide . i have loged over a million miles so far , i use water out of the water hose 100% of the time and all is well. usely trade at 300000 mi. im in a 17 now with 170000. it doesnt know the difference between def and water. lots cheeper

 

i move 5th wheel trailers nation wide . i have loged over a million miles so far , i use water out of the water hose 100% of the time and all is well. usely trade at 300000 mi. im in a 17 now with 170000. it doesnt know the difference between def and water. lots cheeper

HORSE HOCKEY!

No way, no how will water work as a substitute for DEF if the system is actually working. It won't reduce the NOx so the sensor will cause the ecm to post a code and go into limp mode.

So, your truck must be deleted.

 

Good DEF with the Urea should be 32.5%. You can check this with a refractometer. Cummins gives you plus or minus 1.5% on the urea before lights start going off.
Someone ask::::
Link or source for the above statement????

See Attached::::::