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dsalinas1939
Top Member

USA
1325 Posts

Posted - 06/15/2023 :  04:57:22 AM  Show Profile  Reply with Quote
hey guys when the def quality light comes on how does the ecm determan that is it thru the nox sensors? 2017 c2 cummns 6.7. and what is the decomp tube?

Edited by - dsalinas1939 on 06/15/2023 05:03:43 AM

exmod110
Senior Member

150 Posts

Posted - 06/15/2023 :  07:02:28 AM  Show Profile  Visit exmod110's Homepage  Reply with Quote
the decomp tube is where the def is injected into the exhaust between scr and dpf.
looks like there is an ultra sonic density meter in the def tank for quality. they may use other programming and sensors to measure effectiveness of the def being injected like the nox sensor.
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tigger2
Advanced Member

USA
470 Posts

Posted - 06/15/2023 :  09:03:24 AM  Show Profile  Click to see tigger2's MSN Messenger address  Reply with Quote
First check DEF quality with a refractometer to make sure the concentration is good. Look for NOX sensor codes drifting high or low. Check regeneration frequency in the advanced ecm data page on insite.The spread should be even and around 50 or so hrs. between regens. You can also expand the def code on insite to see nox inlet and outlet numbers outlet should be near zero.
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valleybusman
Top Member

USA
808 Posts

Posted - 06/15/2023 :  10:12:43 AM  Show Profile  Send valleybusman an AOL message  Reply with Quote
We had one and checked with a refractometer. That was good and determined the sensor was bad .Replaced and issue went away
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dsalinas1939
Top Member

USA
1325 Posts

Posted - 06/16/2023 :  12:28:28 PM  Show Profile  Reply with Quote
so it reads of a sensor thats part of the header unit and doesnt determine it thru the nox sensors correct?
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tigger2
Advanced Member

USA
470 Posts

Posted - 06/19/2023 :  08:28:42 AM  Show Profile  Click to see tigger2's MSN Messenger address  Reply with Quote
Yes it is. You have to change the whole header asy. to fix it. P/N 04-36002-000 sit down before you ask the price.
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dsalinas1939
Top Member

USA
1325 Posts

Posted - 06/19/2023 :  11:46:35 AM  Show Profile  Reply with Quote
yeah i replaced that but was having hard time clearing the active code i tried everything and didnt work i ended up recalibrating the ecm that the only way i final got them out
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