Do you think it was low on DEF?

I ran my '18 L5P all the way to the DEF EMPTY message. (Intentionally.)

It didn't give a 'Poor quality'
It did give the DEF range warnings at 1000 and 300 miles, and below 300 if did give an update on the remaining 'miles to empty' each time it was started.
After they get to empty, they give a '500 miles to 65 mph speed limit' message and a countdown screen that cannot be cleared from the DIC. (I didn't run that one out to see the 'miles to 55mph message...)

On LML, especially the early ones, 'poor def quality' message was common, and was almost always a sign that one or both NOx sensors needed replacing. It hasn't been a common thing on L5P.

 

How long was the DEF in the tank for? It does degrade over time. Based on other posts on this forum, the way it measures the level and quality is some sort of ultrasonic transducer. I wouldn't be surprised that when the level got low maybe it got a false reading that the quality was low.
Either way, if all is good now, you're probably OK.

 

How long was the DEF in the tank for? It does degrade over time. Based on other posts on this forum, the way it measures the level and quality is some sort of ultrasonic transducer. I wouldn't be surprised that when the level got low maybe it got a false reading that the quality was low.
Either way, if all is good now, you're probably OK.

It's a series of pin sensors. (at least LML was). I'm told that's similar to how the tanks on an RV do it.

6 or 8 years ago there was a bunch of pics posted showing GM's handheld Tech tool displaying the info from the sensors. Each (not very many) would display a 0/1 (so on/off). Then the computer would estimate the level between the sensors.
In any case, it wasn't def level wasn't from a continuously variable gauge like a fuel gauge.
I don't know for sure that they are using the same system on L5P.


As posted I've run my 18 to 'tank empty' message. And on both the LML and L5P almost every time run the level below the 300 mile range before adding any.
Never did this cause a 'DEF poor' message.

The LML I ran did get the 'def poor' and need NOx sensors replaced. It wasn't low when that happened, and it never gave a def quality message again. (ran if for more years after the NOx sensor change than before)

Def poor seems to be an uncommon message now, with the new sensors in the LML's and presumably an updated sensor in the L5P.
But there are many many threads about the def poor message. Few, if any, tested the def and found it was really the problem. When the assumed it was the def and just changed it, the problem would return. Of course, eventually it was determined that really was sensor rather the def (customers) causing the problem. Let to the policy warranty on the def sensors for those early year LML's.

 

99% of the time the DEF is not bad. The message is based on NOx sensor readings. Most of the time its faulty NOx sensors. You can also get this message if the DEF tank runs dry (level sensor stops working)

 

The tank wasn't empty and the fluid in their was blue platinum that I put in about 2 months ago. I'll be honest, I didn't check the date code when I put in the last DEF fluid.

 

You're more than likely fine. Keep driving it, if it comes back, then investigate more. FYI, you can save a lot of cash getting your DEF from the pump at a truck stop. Only $3/gal here in NJ. The truck stops are usually blowing through the stuff so it's always fresh, especially with the amount of truck travel these days.

 

How do you know it didnt go empty?? I can easily drain a tank in 2mo

DEF Quality was probably just fine if youve been driving on it for 2mo

To diagnose you really need to know what codes if any your truck spit out when you got the message.

 

I cant say with %100 certainty that it wasnt empty, but the low DEF warning didnt come on until after the Poor quality warning. Where im at here in souther CA we don't really have DEF at the pump unfortunately. I did hookup my cheesy code reader after restarting the truck the first time after the poor quality message came up but it had no codes. Im not sure my reader would even show them

 

@Fsh4bass ,
Read this thread, especially post #6, and you'll understand where I'm coming from with the level vs quality measurement. What the others said above about the LMLs appear not to apply to our L5P trucks.

DEF thread

 

So in theory the sensor could have gotten a bad reading due to the tank being "low" ?

 

That is my "theory", yes. I find it one hell of a coincidence that the very next day you got the "low" message.

 

Not even the next day, about 30 mins later.

that makes some sense though

 

Yea, if you read that other posting, you'll see why I suggested it. Yes, I'm sure there could be other triggers for that message from the NOX sensors, but it seems plausible it was level related. Obviously, if it comes back soon, then I'm dead wrong. Good luck, hope all is well with your truck.

 

DEF quality is more tightly controlled than the milk we drink, almost to the point of being ridiculous. For autos is has to be 32% urea, not more, not less and anyone who sells DEF has to conform to a very tough standard. Different companies measure DEF quality different ways, but most use performance of the catalyst using sensors pre and post as the guide. Your engine will also go into limp mode if you let it run low, which is a real pain. Given the cost and complexity of a NOX catalyst it is best just to fill the tank at every oil change, it should last till the next one depending on how you are driving. As someone mentioned the best place to get it is in bulk from the place where the trucks get theirs, much cheaper, fresher and probably better quality.

 

I have a 2020 Sierra and soon after changing over to Peak DEF Platinum from regular Blue, i started getting random Poor DEF Quality messages. They normally would clear within 5 minutes or so but i figured it wasn't a coincidence. I notified Peak via email of the issue. After refilling with regular blue DEF, i have not had anymore Poor DEF Quality messages. Also, my dealer said i had the latest software updates so that obviously was not the problem as stated by Peak.

Email response from Peak....
Thank you for contacting us. We are aware of this happening with 2020 GM products. We have learned that General Motors has a computer software update for the exact issue you are having. This is not a DEF issue but rather a GM issue.


Sent from my SM-G981U using Tapatalk

 

I have a 2020 Sierra and soon after changing over to Peak DEF Platinum from regular Blue, i started getting random Poor DEF Quality messages. They normally would clear within 5 minutes or so but i figured it wasn't a coincidence. I notified Peak via email of the issue. After refilling with regular blue DEF, i have not had anymore Poor DEF Quality messages. Also, my dealer said i had the latest software updates so that obviously was not the problem as stated by Peak.

Email response from Peak....
Thank you for contacting us. We are aware of this happening with 2020 GM products. We have learned that General Motors has a computer software update for the exact issue you are having. This is not a DEF issue but rather a GM issue.


Sent from my SM-G981U using Tapatalk

same exact issue. Reached for the platinum because I get tricked by fancy words and had the same exact problem in my 2020

 

I have a 2018 but my fill up prior to the error code was with Platinum

 

I've got a 2011 Denali HD with 30,000 miles on it. A couple of weeks ago I got the message "Diesel Exhaust Fluid Quality Poor" on the dash. When I got home I plugged my scanner in and it had 2 codes relating to the NOX sensors. p2201 & p2202. After doing some research I came across a GM Special Coverage Service Bulletin for the 2011's with the 6.6 Duramax. I also found a letter from GM in my records that matched up with the Service Bulletin. Both of these were about the NOX sensors and extended coverage to 10 years from date vehicle was put into service or 120,000 miles whichever comes first. Took the truck to the dealership and they replaced both sensors at no charge. The service bulletin # is 13386A and is worth looking at if you've got a 2011 with under 120,000 miles and are having issues with the sensors since it doesn't matter if you are the original owner or not. By the way, on the way to the dealership the light and message about "Diesel Exhaust Fluid Quality Poor" went out but the codes were still active when the diagnosis was done. I guess you just can't blame the DEF fluid right off the bat.

 

that message 'DEF Quality' MAY or MAY NOT actually be thrown due to bad DEF

I read a troubleshooting chart.. and sometimes that code is used with the ECM sees that a change in DEF used vs historical data stored .... again its another algorithm to catch emissions cheats putting water in their DEF tank..

 

Glad I found this thread. 2020 GMC 2500 AT4 w/ 5k. Same Peak “Platinum” DEF. Same warnings, low DEF then switches over to poor DEF, sometimes opposite order. Just got another warning today, lasts a mile or two then back to normal. DEF level readings sometimes fluctuate as well day to day. Dealer checked it out two weeks ago & said they have to see it happen since it’s not showing up on their scan. DEF was not low or old, I checked the dates, none were more than 2 months old. I’ll try pump DEF and see what happens.

 

I'm having the same issue with the Platinum DEF. Did your issue resolve when you refilled with normal DEF?

 

doubt pump DEF will make any difference. Something's up with the sensor.

 

Absolutely agree that it’s a sensor and/or software issue. One common factor seems to be that Peak DEF “Platinum” may be setting it off. I’ll switch brands once it’s near empty and follow up in a few months.

 

Same here I'm at 5600 miles, got the def poor quality on the dash. 98 miles, till max speed 65 mph. Only stayed on a few minutes, gauge reads about 75% full. Have only used peak platinum so far

 

30k on O’Reilly DEF... so far....

 

DEF quality is measured by the performance pre and post SCR, obviously whatever "magic dust" they use is poisoning the system. DEF is 32% urea and deionized water, nothing else. Look for the ISO logo on the bottle to show that it complies with the spec

 

What a cash cow…
Thanks for this info on the DEF software hit

 

I did some work with/on DEF when it was first proposed to be used and saw the huge amount of effort it took for companies that store and transport it to get certified. They have to flush their tanks 5 times and then take swabs for testing. The quality and cleanliness standards are higher than for milk or orang juice, seems crazy but that is how the EPA looks at it.

 

I switched over to the Walmart brand, It's been 2 months and around 3000 miles since platinum was used. No more def quality messages

 

There was a lot of unhappy people when this was proposed, and more than a fair share of issues some of which are ongoing. The outcome is very clean emissions from diesels mostly through post treatment which is less of a drama than engine internal systems like EGR. One of the biggest points was always what to do if the DEF is either empty or malfunctions, technically the engine should not be run, but reality is there is nothing wrong with it, a real catch 22. Unlike Europe, the USA hates diesels and they dont make it easy to get them approved and for sale and are watching, AKA the VW engine drama. All car companies tailor their calibration for the test regime, perhaps not as much as VW but not all that different either. I know they are working on alternate catalysts, the most encouraging one that I know of is going to make people really happy as it is the devil fuel itself, ethanol.

 

Seems to me the solution is simple.
Don't use the platinum version....

 

Several posts on the platinum def and the problems its caused. Plain Def works just fine from just about anywhere. Fancy names doesn't mean better

 

I'm just doubtful GM has any tsb that addresses one specific Def.