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Diesel exhaust fluid quality low

44K views 41 replies 20 participants last post by  Tdi'r 
#1 ·
Last night I experienced the dreaded DEF quality low warning light as well as the DIC warning message 99 miles until speed limited to 65 mph. You can't even clear the message on the DIC to look at your other stuff which is a little bit annoying. I have never added any DEF to the car since I bought it in July. It's got over 7500 miles now so I figured that the DEF tank was probably fairly low and who knows when it was filled up originally. The tank holds something like 4.5 gallons which is supposed to last around 10,000 miles, so I figured that it was a fairly safe bet that an entire 2.5 gallon jug would fit. Nope. It almost all fit, though. I'm surprised that in 7500 miles that's all it used. I also got a check engine light shortly after the DEF light came on, but not at the same time. A few miles after filling the DEF quality poor light went out, and a few startups later the check engine light turned off as well. So hopefully a trip to the dealer won't be needed. If I had known how much was still in there I would have drained the tank before refilling, but now I'll just see what happens.
 
#2 ·
Yeah, it would have been nice to have an idea how much is left. I bet the PCM knows how much is in there, but the car just doesn't display that information for you. If I remember correctly, I think the first year of the duramax trucks with DEF had a percentage, but the subsequent years just have a screen that says diesel exhaust fluid level OK just like the Cruze. I guess people already complain that the Cruze diesel is too expensive compared to the other models so adding additional features would jack up the price even more.
 
#3 · (Edited)
The first year in the Duramax's with the DEF (2011) the trucks did not have anything that told you about the DEF level.. Basically the DIC would tell you when it was low and time to fill.. A lot of customers complained about that and they changed it for the 12's.. And on the 12's to current there is nothing that shows a %, the only thing the DIC tells you is "Diesel Exhaust Fluid: Ok" Low, Critical and Empty


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#6 ·
The first year in the Duramax's with the DEF (2011) the trucks did not have anything that told you about the DEF level.. Basically the DIC would tell you when it was low and time to fill.. A lot of customers complained about that and they changed it for the 12's.. And on the 12's to current there is nothing that shows a %, the only thing the DIC tells you is "Diesel Exhaust Fluid: Ok" Low, Critical and Empty


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OK, so the first ones had a percent or a range then? My 2012 Dmax just said OK all the time and that was it.

As a Duramax diesel owner also I have experience with the DEF issues that you are having. The DEF level readings are not reported in percentages because it uses probes to measure the remaining DEF , not a float like a gas gauge would be. The DEF will freeze and that was the reason for the probes and not a float. Must be room for expansion of the DEF.
I had a couple of errors with my 2012 duramax as well.
 
#5 ·
As a Duramax diesel owner also I have experience with the DEF issues that you are having. The DEF level readings are not reported in percentages because it uses probes to measure the remaining DEF , not a float like a gas gauge would be. The DEF will freeze and that was the reason for the probes and not a float. Must be room for expansion of the DEF.
 
#8 ·
It has absolutely nothing to do with your DEF quantity or your DEF quantity for that matter. This is a defect in the sensing system that will leave you stranded and cranky. There is one way it can be cleared. If you run the car on the highway at 70+ MPH for 30+ minutes you will raise the exhaust temp and cook off the crud on the NOx sensors. You could pull your forward NOx sensor and clean the black soot off it and pull your rear NOx sensor and clear the white crusty crud off it. Your dealer will probably change out the entire exhaust system. That is a major job. Every sensor will have to be re calibrated. Do you do a lot of slow city driving ? Or do you drive a lot on the highway. If you tampered with the DEF fluid. Stop. If you ran any "alternate fuels". Stop. I doubt you have.
 
#38 · (Edited)
You know you can edit your posts. If it weren't for that feature, most of my posts would be pretty ugly...lol.

So if the "DEF quality low" indicator warning has nothing to do with DEF quality, then why did adding fresh DEF to my car get rid of the warning almost immediately? I had been driving down the expressway for probably over 20 miles when the warning came up. I stayed on the expressway for at least 15 miles and the light did not go out. Added fresh DEF, light went out in a few minutes. Your theory would seem to suggest that the light would not be expected to come on during the conditions it did with my car. Also, staying on the highway should have fixed it, which it did not. Finally, adding fresh DEF should not have immediately fixed the problem, which it did.
I think your logic here is sound. The "cleaning the exhaust at 70 mph" trick seems to me a totally different problem than your's.

DEF fluid is 66% water 33% fertilizer. There is nothing to go bad as far as the fluid goes.
I heard someone say it was part water and part cow urine....not fertilizer, but as someone said earlier, "I'm not a chemist" to which I'm going to add, "I'm not a farmer either!" LOL Here's a quote from the Air 1 web site:

Diesel Exhaust Fluid (DEF) Production

Diesel Exhaust Fluid (DEF) is made from a high purity urea solution. Urea is produced synthetically from ammonia and carbon dioxide (CO2). Urea is found in every day US products such as hair conditioner, cosmetics, adhesives.

Here's what natural urea is:
u·re·a
yo͝oˈrēə/
noun Biochemistry

noun: urea

  • 1.
    a colorless crystalline compound that is the main nitrogenous breakdown product of protein metabolism in mammals and is excreted in urine.


    Refilling the DEF fluid is part of the free 24 month maintenance provided by the dealership...are some of you not taking advantage of that?

    Don't know if this helps the debate or not???
 
#13 ·
Mine said that the level was 25%. I put in one of the 2.5 gallon jugs and will see how that holds up. It sounded like it was almost full. I refilled once before and made quite a mess when it didn't quite take 2.5 gallons.
 
#14 ·
Wow just saw thing after posting another thread. I got the light as well this weekend. Then as I was rushing to the dealer on the highway, 70+ MPH it went out. Maybe I need to educate my dealer since they had no idea.
 
#15 ·
I fear that this may become a problem for some people. We need to pool our experiences so we can help the dealers fix it. I can say a few things for certain. It has absolutely nothing to do with the fluid so any time the dealer spends draining flushing and replacing fluid is a waste of time. It has nothing to do with fluid temperature or quantity. It seems to go away when the car is run hard which leads me to believe that higher EGTs are a factor. I think this problem is related to soot on the front NOx sensor or crystallized crud on the rear NOx sensor. I would like to know from the people who have had this happen what type of driving they do and how often the car gets run hard. I think because its an emission problem its going to be a little more difficult to fix because of EPA reg's. If people find a work around they might be afraid to share it publicly.
 
#16 ·
Mine started just after the Thanksgiving holiday when the wife and i were taking short trips around town for 4-5 days. On Saturday when i was rushing to the dealer and doing 70+ on the highway for 10 or so miles it went out. Dealer did a recalibration of the sensor and checked the fluid. They test drove it a little and the warning did not return.

In general I drive mostly highway between 60 and 70 depending on traffic. My ride home sees about 10 miles of medium to heavy highway traffic then its 60+ for the remaining 35. I do about 80ish miles per day to and from work.
 
#18 ·
Thanks, The scary part is that when you get the message you really only have 100 miles to clear it. Once the computer limits your speed to 65 mph max you cant build up enough heat in the exhaust to clear it. If I get the message again I will pull and clean the NOx sensors. The system this car uses to monitor the NOx reduction is weak. next generation diesels will use an ammonia sensor to determine the effectiveness of the system.
 
#19 ·
65 is more than enough speed during a DPF regen. There is a long stretch of road that I often drive on where the speed limit is 45-55 the whole time. I've seen my car complete a regeneration cycle start to finish on that road a number of times. The diesel owners supplement says anything above 30 mph is enough if you get the cleaning exhaust keep driving message.
 
#20 ·
This isn't related to the DPF regen. What they're talking about is getting high enough temps through your exhaust system to clear off the gunk off the NOx sensors, which are farther down the pipe than the DPF.

Although, I would imagine a DPF regen would help as it raises the EGT.
 
#22 ·
And you should be able to get the exhaust hot enough at 65mph if you manually shift it down a couple of clicks and run it for a bit.

The users manual for my Korean-built cruise says that you clear the DPF warning by "running at 2000rpm or more for 20 minutes or more." I've cleared it by running at 60km/h (~35mph) in second, just going around the block a few dozen times!

If that clears the DPF, it should do the same for the DEF.
 
#23 · (Edited)
At least in big trucks, what raises exhaust gases the most is running a heavy load up a hill, they wouldn't really increase much just from high rpm's.

In fact lugging the engine under load raises exhaust gases faster then anything else. If going up a hill that I could pull at say 1,300rpm in a gear and the engine isn't quite to lugging point yet the temps will be screaming but if I downshift and pull the hill at 1,800-1,900rpm the motor will be screaming (2,200rpm redline) but exhaust temps will be much lower.

No I am not recommending lugging your cruze :) , Just pointing out I do not believe running high rpm's raises them that much but it does increase flow which I think is the point with a regen of your DPF. Heat AND airflow.

Heavy turbo boost at lower rpm with less airflow = heat buildup
 
#24 ·
I agree and I tried running higher RPMs and it didn't work. High load up a hill works best as stated. It has nothing to do with the DPF, the DEF quantity or DEF quality. The DEF fluid goes through an SCR (selective catalyst reduction unit) think of it as a catalytic converter. There are NOx sensors one each side. Soot builds up on the front and white crud builds up on the back one. High EGTs burn it off. The computer is not seeing a big enough reduction in NOx between the front and the back so it assumes you tampered with the DEF fluid and posts the message.
 
#25 ·
So if the "DEF quality low" indicator warning has nothing to do with DEF quality, then why did adding fresh DEF to my car get rid of the warning almost immediately? I had been driving down the expressway for probably over 20 miles when the warning came up. I stayed on the expressway for at least 15 miles and the light did not go out. Added fresh DEF, light went out in a few minutes. Your theory would seem to suggest that the light would not be expected to come on during the conditions it did with my car. Also, staying on the highway should have fixed it, which it did not. Finally, adding fresh DEF should not have immediately fixed the problem, which it did.
 
#29 ·
Maybe it was a legitimate problem. I know very little about DEF systems, but the dealer I bought mine from told me that DEF can go bad but that adding fresh DEF to the tank will refresh the whole batch and solve the problem. Don't ask me how; I'm not a chemist.
 
#32 · (Edited)
Someone has told me that DEF degrades with both heat and time. If the DEF was the original fill, ran through the whole summer, and was 6 months (or more, depending on when the car was built) old, could it be that the combination of time and heat did actually cause the DEF that was good in July to be of low quality by December?
 
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