# Diesel exhaust fluid quality low



## Jorday (Jul 30, 2013)

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.


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## WhiteAndBright (Mar 4, 2013)

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


Sent from AutoGuide.com Free App


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## Sperry (Aug 3, 2013)

Looking at my read out on Friday and it said 33%.. all the other times it was saying DEF OK. but it does tell you as it gets lower.. I'm around 14000 miles and surprised at how long it's lasted


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## Schmelz (Nov 24, 2013)

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.


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## Jorday (Jul 30, 2013)

WhiteAndBright said:


> 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
> 
> 
> Sent from AutoGuide.com Free App


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. 



Schmelz said:


> 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.


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## Sperry (Aug 3, 2013)

View attachment 49737


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## Scott M. (Apr 23, 2013)

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.


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## Scott M. (Apr 23, 2013)

Meant to write> It has nothing to do with quality or quantity. Wrote quantity twice. Duh.


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## mc2crazy (Oct 25, 2013)

If you live up north can the DEF freeze?


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## Gator (Jul 14, 2013)

mc2crazy said:


> If you live up north can the DEF freeze?


Yes it can freeze. its 67% water 33% fertilizer. You have a heater in the tank. I had a tank freeze up only once on my Semi around two Years ago. Last winter trouble free. I don't think it will freeze solid with the mix of fertilizer.


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## boraz (Aug 29, 2013)

mc2crazy said:


> If you live up north can the DEF freeze?


it will freeze at 5 f...but it thaws out when you drive, the tank is heated


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## diesel (Jun 8, 2013)

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.


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## CosmosGoat (Sep 23, 2013)

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.


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## Scott M. (Apr 23, 2013)

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.


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## CosmosGoat (Sep 23, 2013)

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.


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## DieselMan33 (Oct 13, 2013)

My commute to work is only 6 miles will numerous stop lights but stretches I get up to 65mph. I also make short trips around town and have yet to have this message come up. Approaching 1500 miles on the car, I will be on the look out.


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## Scott M. (Apr 23, 2013)

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.


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## Jorday (Jul 30, 2013)

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.


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## PanJet (Jun 18, 2013)

Jorday said:


> 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.


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.


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## Jorday (Jul 30, 2013)

Fair enough I see what you're saying, but the "gunk on one of the sensors" theory doesn't seem to make any sense with what happened to my car.


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## grs1961 (Oct 23, 2012)

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.


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## KpaxFAQ (Sep 1, 2013)

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


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## Scott M. (Apr 23, 2013)

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.


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## Jorday (Jul 30, 2013)

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.


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## CosmosGoat (Sep 23, 2013)

I have a sneaking suspicion this is going to come up more as more TDs are sold and GM will have to address it in some manner.


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## GotDiesel? (Sep 9, 2013)

I have always said "Diesels have two speeds" Dead Stop and Wide Open . When possible give it the Italian Tune Up and put your foot into it ,that will clean it out.


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## Scott M. (Apr 23, 2013)

GM needs to do a software mod to the ECU. The duramax diesels went through this with some of their trucks. This is all Al Gores fault. Stupid unrealistic emissions standards. I wish the EDC17 ECU was able to be flashed by the OBD port.


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## PanJet (Jun 18, 2013)

Jorday said:


> 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.


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.


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## Gator (Jul 14, 2013)

DEF fluid is 66% water 33% fertilizer. There is nothing to go bad as far as the fluid goes.


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## XtremeRevolution (Jan 19, 2012)

Jorday said:


> 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.


It depends on the dilution of water. The DEF quality indicator is there to make sure people don't just fill that tank with straight water. If your water percentage is too high, that will go off.

Sent from mobile.


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## revjpeterson (Oct 2, 2013)

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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## Jorday (Jul 30, 2013)

It does have a shelf life supposedly.


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## Scott M. (Apr 23, 2013)

The DEF quality poor indication can of course be an indication of poor DEF quality but I would bet that it is not the case in your circumstance. I can't argue with your results though. I am just sharing my experiences with this issue. That's what these forums are for. People post, you decide. The dealers are not up to speed on this and they will just "carpet bomb" the issue with parts until it goes away. I want to know why. I hope your problem is solved. Please post it it ever comes back.


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## Jorday (Jul 30, 2013)

Yeah, I'll definitely be posting up if I have any further issues. I'd definitely be curious to see what really happened, but how would you know for sure at this point? I really hate taking my stuff to the dealer unless I absolutely have to. Hve you noticed the NOx sensors seem to be prone to electrical problems as well as the buildup of deposits? I had some problems with my dmax truck going into limp mode due to corrosion in the wire connector for the rear NOx sensor. It didn't set a DEF poor warning, the truck just went directly into limp mode and wouldn't go over 55 mph. My buddies Dodge did the exact same and took several trips to the dealer before they finally just replaced the sensor which fixed it.


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## Scott M. (Apr 23, 2013)

True. We cant fix it if it ain't broke. I think we have to wait and see how it goes. If I get it again I plan to do some experiments with the sensors.


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## gyrfalcon (Dec 27, 2013)

Does anyone remember how much DEF was in your tank when you left the dealership? I have a new car and it shows 36% which I thought was weird.


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## ParisTNDude (Oct 7, 2013)

Scott M. said:


> Meant to write> It has nothing to do with quality or quantity. Wrote quantity twice. Duh.


You know you can edit your posts. If it weren't for that feature, most of my posts would be pretty ugly...lol.



Jorday said:


> 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.



Gator said:


> 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???


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## revjpeterson (Oct 2, 2013)

gyrfalcon said:


> Does anyone remember how much DEF was in your tank when you left the dealership? I have a new car and it shows 36% which I thought was weird.


Mine was full, since the dealer topped it off at delivery. My indicator went from "OK" to "35%" just before my first regular service around 6800 miles.


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## Tdi'r (Jan 5, 2014)

gyrfalcon said:


> Does anyone remember how much DEF was in your tank when you left the dealership? I have a new car and it shows 36% which I thought was weird.


Interesting, mine showed the same thing (I think 35%) when I took delivery of the car. I questioned the sales person, "did they forget to fill the tank?" He responded, "No, that percentage increases as you drive." I just smiled and nodded my head. Even my wife on the way home said, "Wow, GM has engineered a system where fluid is manufactured as you drive, they really are finding new roads..." It was a good laugh at the time. ANYWAY, the next day the message said the standard "Level OK." So either it really is full and just needed to reset itself... or it has 35% or <. Either way, I'm not worried about it. 
Thanks for the post, I find it intriguing that my initial observation wasn't unique.


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## diesel (Jun 8, 2013)

Tdi'r said:


> Interesting, mine showed the same thing (I think 35%) when I took delivery of the car. I questioned the sales person, "did they forget to fill the tank?" He responded, "No, that percentage increases as you drive." I just smiled and nodded my head. Even my wife on the way home said, "Wow, GM has engineered a system where fluid is manufactured as you drive, they really are finding new roads..." It was a good laugh at the time. ANYWAY, the next day the message said the standard "Level OK." So either it really is full and just needed to reset itself... or it has 35% or <. Either way, I'm not worried about it.
> Thanks for the post, I find it intriguing that my initial observation wasn't unique.


35% is where they start dispalying a number. So, at 36% (margin of error) you are "OK" but at 35% you will see a number. That being said, after I fill it up, it takes a few miles to go from whatever the % reading was to "OK". Hope that helps.


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## Tdi'r (Jan 5, 2014)

diesel said:


> 35% is where they start dispalying a number. So, at 36% (margin of error) you are "OK" but at 35% you will see a number. That being said, after I fill it up, it takes a few miles to go from whatever the % reading was to "OK". Hope that helps.


That helps explain it. Thanks for the info!!


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