[sergeantspud]

Okay for a 3rd highjack on this thread? It sounds like I'm late to the party, from what I gather I might be close to bumpinalta (~1600mi round trip to rose bowl from northern utah) and we could have shared parts.

So anyways I got the DEF quality poor light on, I drive 45mi one way all highway 65mph+ to work every day. 2014 cruze, original owner, 154k miles. I had the NOX recall done early on, like sub 50k miles I think. Only recent repair is p227b which I had the dealer fix with a new ECU, that was about 1000 miles ago. I did the DEF heater around 20k miles ago.

Pulling the codes on gretio I get: P249D and P204B. We all know what P249D is but P204B appears to be: "Reductant pressure sensor performance general failure". Both of these code are in "history" though so I don't know how long ago they were present.

First thing I did was pull the DEF injector, the nozzle looks clean and was visibly wet. My assumption is that the wetness on the nozzle tip and inside the pipe is indicative that DEF is being injected. I cleaned the external surfaces and reinstalled.

Pulled up Gretio and ran a service regen, then a DEF quality test. Failed. NOX1~58ppm and NOX2~20ppm

Replaced NOX2. I was lucky enough to find a OEM one on rockauto go in stock briefly, I sort of feel bad for the other guys waiting and looking for one. Anyways I installed it, drove it around 10 miles, service regen, DEF quality test. Failed. NOX1~65ppm NOX2~16ppm

So now I'm thinking maybe my pump or injector is not functioning right. I pulled the injector and performed a DEF quantity check. It spit out about 50ml of fluid which is a pass according to the bulletin I referenced. So that would rule out my pump and injector.

Drained and filled with a new bottle of BlueDEF (date code 2/21 - a little old but I read 1 year is still okay)

Ran a DEF fluid quality again to attempt to purge the DEF lines- NOX1~68ppm NOX2~14ppm. Then I ran a service regen, and a final DEF fluid quality: NOX1~70ppm NOX~12ppm.

I feel like every time I fluid quality test it gets slightly better, but I'm worried about stressing the DPF with too many service regens. At this point I'm not sure what to do. Wondering if maybe NOX1 is under reporting, or my SCR is just getting tired. Any one have any thoughts?

 

[15cruzediesel]

It might not be passing because of the "history" codes.

It might just need a drive cycle completion to go back to normal IF it doesn't throw any new or previous codes during the drive cycle.

 

[sergeantspud]

That did it!!! After work today I pulled and inspected the NOX1 sensor, didnt look too sooted up but I cleaned it with MAF cleaner and reinstalled. Then I ran a DEF quality test, failed NOX1~70ppm NOX2~19ppm. That's about the time I saw your message and wondered, maybe I should clear the codes and try again. I tried to clear them on Gretio but could not get it to go through, KOEO nor KOER. I pulled up a different scanner app and cleared that way then went back to gretio to do another DEF quality test. PASSED! NOX1~70ppm NOX2~18ppm. No more death clock countdown!

To clarify, my CEL was not on. It went on right after it started the death clock countdown but the CEL cleared about halfway home that day and has remained off since then. Now hopefully it stays cleared. I'm not sure what ended up actually being the problem, all I physically did was: NOX2 sensor replacement, DEF drain and fill, DEF injector cleaned, NOX1 sensor cleaned. I performed at least 4 service regens and probably around 7 or 8 DEF quality tests in between all those actions. Advice for anyone else, clear the codes before trying to clear the countdown with a DEF quality test!

 

[15cruzediesel]

That did it!!! After work today I pulled and inspected the NOX1 sensor, didnt look too sooted up but I cleaned it with MAF cleaner and reinstalled. Then I ran a DEF quality test, failed NOX1~70ppm NOX2~19ppm. That's about the time I saw your message and wondered, maybe I should clear the codes and try again. I tried to clear them on Gretio but could not get it to go through, KOEO nor KOER. I pulled up a different scanner app and cleared that way then went back to gretio to do another DEF quality test. PASSED! NOX1~70ppm NOX2~18ppm. No more death clock countdown!

To clarify, my CEL was not on. It went on right after it started the death clock countdown but the CEL cleared about halfway home that day and has remained off since then. Now hopefully it stays cleared. I'm not sure what ended up actually being the problem, all I physically did was: NOX2 sensor replacement, DEF drain and fill, DEF injector cleaned, NOX1 sensor cleaned. I performed at least 4 service regens and probably around 7 or 8 DEF quality tests in between all those actions. Advice for anyone else, clear the codes before trying to clear the countdown with a DEF quality test!

Sweet. Nice to hear a success story for a change.

 

[Snipesy]

That did it!!! After work today I pulled and inspected the NOX1 sensor, didnt look too sooted up but I cleaned it with MAF cleaner and reinstalled. Then I ran a DEF quality test, failed NOX1~70ppm NOX2~19ppm. That's about the time I saw your message and wondered, maybe I should clear the codes and try again. I tried to clear them on Gretio but could not get it to go through, KOEO nor KOER. I pulled up a different scanner app and cleared that way then went back to gretio to do another DEF quality test. PASSED! NOX1~70ppm NOX2~18ppm. No more death clock countdown!

To clarify, my CEL was not on. It went on right after it started the death clock countdown but the CEL cleared about halfway home that day and has remained off since then. Now hopefully it stays cleared. I'm not sure what ended up actually being the problem, all I physically did was: NOX2 sensor replacement, DEF drain and fill, DEF injector cleaned, NOX1 sensor cleaned. I performed at least 4 service regens and probably around 7 or 8 DEF quality tests in between all those actions. Advice for anyone else, clear the codes before trying to clear the countdown with a DEF quality test!

These newer vehicles are very temperamental on when you can clear codes. That’s why it says stuff like “Conditions not Correct.”

Generally if you power off and then on again (no start) your chances are better.

Just fair warning good chance the other tool did not clear codes. Most tools just send the message but do not check if clearing actually worked.

Worse case scenario just drive the vehicle a lot. 10 minute drives. Drive cycles clear codes.

 

[BDCCruze]

@Snipesy - Do these cars do DEF quality testing on their own periodically? I can't imagine the intention from GM is that you must have it done at a dealer. Shouldn't the cars 'self heal' after a false positive code? Is draining the DEF and refilling and driving it until death clock countdown goes away enough?

 

[Snipesy]

@Snipesy - Do these cars do DEF quality testing on their own periodically? I can't imagine the intention from GM is that you must have it done at a dealer. Shouldn't the cars 'self heal' after a false positive code? Is draining the DEF and refilling and driving it until death clock countdown goes away enough?

During normal highway driving yes.

The advantage of the quality test is it’s stationary. And after 4mph it’s basicially your only option.

 

[15cruzediesel]

@Snipesy - Do these cars do DEF quality testing on their own periodically? I can't imagine the intention from GM is that you must have it done at a dealer. Shouldn't the cars 'self heal' after a false positive code? Is draining the DEF and refilling and driving it until death clock countdown goes away enough?

Anytime nox1 and nox2 are working correctly it is doing a def quality test.

Let's say you put "bad" def in the car:

It will command the appropriate amount of def to control nox emissions.

If at some point nox emissions are excessive and can't be controlled, it would throw a def quality poor.

This is assuming everything is working correctly, since the amount of def needed isn't working.

The car would be correct and the def fluid isn't effective in this scenario.

I know when you look at block diagrams for solving diesel emissions problems, they all contain a concern for tampering when it comes to def.

 

[Snipesy]

The car would be correct and the def fluid isn't effective in this scenario.

I know when you look at block diagrams for solving diesel emissions problems, they all contain a concern for tampering when it comes to def.

Those we’re written back in like 2011 where they wrongly thought DEF Quality would be important. And that people would try and fake the system.

In reality it’s insanely rare. And DEF QUALITY errors means the SCR is just not working as effective as it should be. That could be a sensor, injector issue, etc… but it’s rarely because of def quality.

This is because said error comes from monitoring NOx sensor 1 and 2. And thus it’s purely a measure of SCR efficiency. Not DEF quality.

GM did change this. And now new diesels use a dedicated quality sensor. But not on the Gen 1.

 

[15cruzediesel]

Those we’re written back in like 2011 where they wrongly thought DEF Quality would be important. And that people would try and fake the system.

In reality it’s insanely rare. And DEF QUALITY errors means the SCR is just not working as effective as it should be. That could be a sensor, injector issue, etc… but it’s rarely because of def quality.

This is because said error comes from monitoring NOx sensor 1 and 2. And thus it’s purely a measure of SCR efficiency. Not DEF quality.

GM did change this. And now new diesels use a dedicated quality sensor. But not on the Gen 1.

Sorta.

You have to ask yourself what an scr needs to work and it most be fresh or it won't work.

Without the oxidizing agent the scr is worthless to meet the emissions requirements the government imposes.

I agree it is probably rare to be bad.

Sadly stealerships have made a ton of money charging people to flush and refill def tanks.

 

[TyGeR]

Hello guys, 2 years after I resolved my issue (the other post someone one linked) Im back to having the same issue. This time I have a P20EE code, I replaced the tank heater again with no luck, then replaced the upstream Nox1 sensor, (toe P20EE code) it cleared the fault for 30 mins or so but came back. The tablet I use with my USB cable took a dump so Im debating on getting another tablet an see if the USB cable will work with the Gretio app or buy the MX+ OBD tool and use it bluetooth with my phone. The guide that Snipesy put together looks like really good info. Once I get either a new tablet or the MX+ tool I'll start working on my car again an hope I can get everything cleared up!

On a side note, its funny I already have the exact BAFX scanner that he said will not work. I use it in my truck pulling my camper to watch oil and trans temps with TorquePro

 

[TyGeR]

I wanted to post an update. I ordered the MX+ OBD tool that Snipesy posted in the Youtube video. After swapping the DEF tank heater again and the NOX1 sensor, I ran the DEF Fluid Quality Test per the guide FOUND HERE. My car passed the test, after the test finished and my car showed passed the DEF Fluid quility poor fault cleared. My car is out of limp mode and back on the road. I understand why all the emission junk are on newer vehicles but I still wish I could rip it all out and tune it out of my car so I never deal with it again!