# Diesel Exhaust Quality poor (I know there are a ton of threads on this but I’m new to this and haven’t found exact issue I’m having)



## Snipesy (Dec 7, 2015)

Since it’s limited to 3/4 mph. You’ll have to do a def fluid quality test to diagnose. That will allow you to look at the PIDs and see where the issue is. Don’t rely on DTCs.


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> Since it’s limited to 3/4 mph. You’ll have to do a def fluid quality test to diagnose. That will allow you to look at the PIDs and see where the issue is. Don’t rely on DTCs.


How do I do a def fluid quality test?


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## xlvchampions1 (May 19, 2021)




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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> How do I do a def fluid quality test?


Depends how much you want to spend

Gretio - Automotive Scan Tool - Apps on Google Play


For the pressure sensor code.. That should be a part of the def pump but would have to look at the manual for that one.

ALLDATAdiy.com - Select Vehicle is a good cheap legal source for manuals.


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> Depends how much you want to spend
> 
> Gretio - Automotive Scan Tool - Apps on Google Play
> 
> ...


So I guess my question is why test the quality of the def? Wouldn’t it be easier to drain def tank, clean it out and refill with fresh fluid?

and as far as the codes go. Do they seem to point to a faulty Def Heater? Or am I wrong in that assumption


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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> So I guess my question is why test the quality of the def? Wouldn’t it be easier to drain def tank, clean it out and refill with fresh fluid?
> 
> and as far as the codes go. Do they seem to point to a faulty Def Heater? Or am I wrong in that assumption



DEF Fluid Quality test is a thing the car does to verify a lot of things. One of them being the quality of the DEF. Its like a 30 minute process.

More than likely the def in the tank is fine and there is no need for it to be replaced. And I guess not to appeal to my knowledge but yeah I have serviced at least 100 trucks with this issue. Not once has 'DEF Quality Poor' actaully been poor quality.


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## xlvchampions1 (May 19, 2021)

Ok so is there a way to test the def pump heater? With a multi meter or something?


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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> Ok so is there a way to test the def pump heater? With a multi meter or something?



They are just resistors... So technically yes.

However it can be hard as the resistance will change as they heat up and such. Which means you have to test with all that plugged in annnnd yeah it gets complicated. We just replace the entire unit and don't bother with this stuff.


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## xlvchampions1 (May 19, 2021)

So is it safe to say that with the codes the car has that the def pump heater is probably my culprit? The thing that gets me is it’s like a HARD fault as it doesn’t go away and come back. Almost like somethings unplugged or not getting power. But I’m new to these little diesels so maybe it’s a common thing with this issue. That I don’t know.


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## BDCCruze (Jul 12, 2017)

xlvchampions1 said:


> Ok so is there a way to test the def pump heater? With a multi meter or something?


Yeah, the primary connector should be between 3.5 and 4.5 Ohms IIRC. Mine failed at around 11 Ohms.

Test it on the old one first.


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## Snipesy (Dec 7, 2015)

Why don’t you first unhook big blue and douse it with electric contact cleaner.


Pull the big lever OVER and it just pulls apart.


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> Why don’t you first unhook big blue and douse it with electric contact cleaner.
> 
> 
> Pull the big lever OVER and it just pulls apart.


*You’re saying to try unhooking the main LARGE connector, cleaning it, and rebooking it?

I tried cleaning all of the connectors since it was pulled apart once before to install new pump by previous owner. I also checked pins to make sure none were bent or broken.*

Does anyone know the relay/fuse for the def heater? I looked at cover but didn’t find any that stood out as heater for sure or not


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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> *You’re saying to try unhooking the main LARGE connector, cleaning it, and rebooking it?
> 
> I tried cleaning all of the connectors since it was pulled apart once before to install new pump by previous owner. I also checked pins to make sure none were bent or broken.*
> 
> Does anyone know the relay/fuse for the def heater? I looked at cover but didn’t find any that stood out as heater for sure or not


It’s powered by a mix of the ECM and GPCM. If that doesn’t make any sense it’s cause it doesn’t. Ask GM.

In other news it’s the fuse labeled ignition and the car probably wouldn’t start at all if it was out.

It is possible the GPCM is dead. But again I have my doubts.


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> It’s powered by a mix of the ECM and GPCM. If that doesn’t make any sense it’s cause it doesn’t. Ask GM.
> 
> In other news it’s the fuse labeled ignition and the car probably wouldn’t start at all if it was out.
> 
> It is possible the GPCM is dead. But again I have my doubts.


Lol, nothing can ever be simple hahah. I’m assuming it’s not “dead” as I currently have the heater removed and turned key on to roll up windows in car. When I did that I heard the def pump running in the truck (at least I think that’s what it was) 

so here’s my question: original owner said the def message came on for him a few weeks back. He kept driving vehicle and speed limit kept going down on him until it reached the point it’s currently at. He had a buddy swap the def pump thinking that was issue (I have oe one in trunk as well) but it didn’t sound like they were very mechanically inept as he hadn’t even attempted to read any codes in the system or anything and kept trying to fill def tank over and over overflowing each time from the looks of it.
The vehicle immediately shows the def system message when you start vehicle w def light flashing. So would it make sense with all things currently known and the symptoms would the def fluid heater make sense or am I going down the wrong path? I’m limited on my time to work on it so I’m trying to get it fixed ASAP. I’ve ordered a def heater already but I want to make sure I get this thing fixed & going again for that reason.


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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> Lol, nothing can ever be simple hahah. I’m assuming it’s not “dead” as I currently have the heater removed and turned key on to roll up windows in car. When I did that I heard the def pump running in the truck (at least I think that’s what it was)
> 
> so here’s my question: original owner said the def message came on for him a few weeks back. He kept driving vehicle and speed limit kept going down on him until it reached the point it’s currently at. He had a buddy swap the def pump thinking that was issue (I have oe one in trunk as well) but it didn’t sound like they were very mechanically inept as he hadn’t even attempted to read any codes in the system or anything and kept trying to fill def tank over and over overflowing each time from the looks of it.
> The vehicle immediately shows the def system message when you start vehicle w def light flashing. So would it make sense with all things currently known and the symptoms would the def fluid heater make sense or am I going down the wrong path? I’m limited on my time to work on it so I’m trying to get it fixed ASAP. I’ve ordered a def heater already but I want to make sure I get this thing fixed & going again for that reason.


No I do not believe the heater is the problem.

However the tank heater is basically that entire unit that comes out with numerous other gizmos. So it’s a start.


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> No I do not believe the heater is the problem.
> 
> However the tank heater is basically that entire unit that comes out with numerous other gizmos. So it’s a start.


So what else would cause those codes?


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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> So what else would cause those codes?


You have to start testing.


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> You have to start testing.


Understood. But where do I begin? Lol. I’m scratching my head over where to begin.


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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> Understood. But where do I begin? Lol. I’m scratching my head over where to begin.


It is going to be EXTREMELY difficult to test without a proper scan tool. That's why I made that Gretio app. Since otherwise the tools will at minimum be like $800. But $2000 or $3000 is more realistic unless you like China crap.

In particular since its limited to 4 mph. You are boned. The car is simply unable to clear the issue without doing the 'Def Fluid Quality Test' because it will never reach the conditions needed to clear the countdown.

Okay anyway since you have bought a new heater I would start by replacing that. And just not bother with anything else for now. When you get it you will clear dtcs, perform a service regen, and then perform the fluid quality test. Allow the fluid quality test to go for 30 minutes annd if it doesnt stop on its own go ahead and stop it yourself.

After that go ahead and post the results (what new dtcs are there?) here and we can go from there.

Yes you need the app. No you cant just throw parts at it. Yeah I know. Its stupid.


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> It is going to be EXTREMELY difficult to test without a proper scan tool. That's why I made that Gretio app. Since otherwise the tools will at minimum be like $800. But $2000 or $3000 is more realistic unless you like China crap.
> 
> In particular since its limited to 4 mph. You are boned. The car is simply unable to clear the issue without doing the 'Def Fluid Quality Test' because it will never reach the conditions needed to clear the countdown.
> 
> ...


No I’m completely cool with getting this app. I didn’t know about it. Can I download it to IOS and use my Bluetooth obd connector with it? And I’m assuming the “def fluid quality test” is something completed with the scan tool? I misunderstood earlier and thought you meant I actually had to test the fluid like a science experiment lol


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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> No I’m completely cool with getting this app. I didn’t know about it. Can I download it to IOS and use my Bluetooth obd connector with it? And I’m assuming the “def fluid quality test” is something completed with the scan tool? I misunderstood earlier and thought you meant I actually had to test the fluid like a science experiment lol


Yes. The iOS version isn’t in App Store but you can join its beta. There’s a lot of things lacking in it but it’ll get the job done.








Gretio Testing Guide


Gretio Testing Guide Last Updated February 20, 2021 https://testflight.apple.com/join/R7HRurKT Needed Materials and Software OBDLINK MX+. May be bought from Amazon or directly from https://www.scantool.net Any iOS device with iOS 13.4 or greater. Gretio Testflight App Installed OBDLINK ...




docs.google.com




You need an OBDLINK MX+ for that. Blue drivers, plx kiwi, etc… these are not powerful enough to do this stuff.


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> Yes. The iOS version isn’t in App Store but you can join its beta. There’s a lot of things lacking in it but it’ll get the job done.
> 
> 
> 
> ...


so is it better to use on an android device? And I have a Innova wireless obd11 connector. Will that suffice?


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## xlvchampions1 (May 19, 2021)

Snipesy said:


> Yes. The iOS version isn’t in App Store but you can join its beta. There’s a lot of things lacking in it but it’ll get the job done.
> 
> 
> 
> ...











this is the one I currently have.


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## Snipesy (Dec 7, 2015)

xlvchampions1 said:


> View attachment 292215
> 
> this is the one I currently have.


Wont work sadly. At best it will connect but be insanely unstable.


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## dougc905 (May 24, 2015)

Just had that message for the first time at 182,000 km. In my recollection, a bad def tank heater results in a discrete error code, not the fluid quality message. Perusing threads here led me to believe that it was an oil overfill problem since I had just had the oil changed. Drained oil out of the pan and achieved nothing. Clearing the codes with my scanner did nothing. Brought it to the dealer who diagnosed one of the NOx sensors. $1000 later, the problem seems to be solved. My advice, bring it to a dealer and consider it part of the purchase price of the car. Once you get it running, you’re going to love the car.


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## Cruz15 (Mar 17, 2016)

Snipesy said:


> Depends how much you want to spend
> 
> Gretio - Automotive Scan Tool - Apps on Google Play
> 
> ...


Does the Gretio app have more features than the Bi-scan app? Does it function with the 1.6 Liter engine?


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## Snipesy (Dec 7, 2015)

Cruz15 said:


> Does the Gretio app have more features than the Bi-scan app? Does it function with the 1.6 Liter engine?


Yes. And yes.

A lot more. BiScan has like 20 controls and 60 PIDs.

Gretio has like 5000 PIDs and around 200 controls.


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## Cruz15 (Mar 17, 2016)

Snipesy said:


> Yes. And yes.
> 
> A lot more. BiScan has like 20 controls and 60 PIDs.
> 
> Gretio has like 5000 PIDs and around 200 controls.


I'm going to get it then. Thank you.


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