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P24C6 code

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code p24c6
30K views 36 replies 10 participants last post by  suzdar ismaill 
#1 ·
Got the dreaded exhaust fluid quality low message with its 99 mile countdown to death. I drove it hard for almost 80 miles and it went away but I am left with a check engine light and a P24C6 code. It drives me crazy that I cant get the definition on google. Does anyone know what the code means ?
 
#6 ·
A lot of the ODBII codes have been standardized across manufacturers.
 
#5 ·
Nope I can't find it as hard as I tried. I even went through the European diesel manual but it looks like their systems there don't have the DEF therefore the code isn't in there (Figures). Good luck hopefully a GM tech sees this and lets you know what the code is. However if you were to get the code reset I bet you it wouldn't come back.
 
#11 ·
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#8 ·
Thanks ! This forum is great. On the way into work I again got the exhaust fluid poor message and countdown after 20 miles since resetting. I was passing by my dealer anyway so I popped in and left with a loaner Chevy Captiva. Looks like I will be getting a new particulate matter sensor. I thought that was just for monitoring health of the DPF. I dont know if the two problems are related. I am going to make them drive the car for 30 miles after reset to see if its really fixed.
 
#9 ·
I am curious if it's just the sensor. A couple other people have had a similar message but I don't recallwhat the root cause was. Keep us posted!
 
#10 ·
I'm curious as to the outcome of this problem as well .....

After doing a bit of reading, it seems to me the particulate matter sensor fault (P24C6) should be unrelated to the exhaust fluid quality message. As stated is the manual I copied earlier the P24C6 code is caused by the particulate matter sensor temperature being out of tolerance, but the 'exhaust fluid low quality' message is generated by a comparison of upstream and downstream NOx sensors not showing enough NOx reduction across the SCR (Selective Catalyst Reduction) ...... meaning the DEF fluid is weak.

I can't figure how they're related ......

:unsure::dizzy::dazed002:
 
#28 ·
I'm curious as to the outcome of this problem as well .....

After doing a bit of reading, it seems to me the particulate matter sensor fault (P24C6) should be unrelated to the exhaust fluid quality message. As stated is the manual I copied earlier the P24C6 code is caused by the particulate matter sensor temperature being out of tolerance, but the 'exhaust fluid low quality' message is generated by a comparison of upstream and downstream NOx sensors not showing enough NOx reduction across the SCR (Selective Catalyst Reduction) ...... meaning the DEF fluid is weak.

I can't figure how they're related ......

:unsure::dizzy::dazed002:
dpf needs def to function
 
#14 ·
on our work trucks with dpf's code will come up low def quality

there is no sensor measuring the quality of the def on the truck whatsoever.

the computer notices poor nox conversion, the mechanic then verifies the def quality with a refractor dealiebob, if it checks out, the issue is in the dpf itself....if there is an actual issue, or just a bad sensor, wire, harness etc....signalling the computer


I HAVE ZERO IDEA IF THE CRUZE ACTUALLY HAS A DEF QUALITY SENSOR, guessing no, guessing its similar to what i described.

GUESSING
 
#15 ·
Interesting theory and it sounds likely to me that the Cruze would not check the fluid itself, but instead check the anticipated result of what it does.
 
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#16 ·
Update. The dealer is doing what they do best. Deflecting from the problem. The particulate matter sensor hard failed and they changed it. Good job with that simple task. That sensor has nothing at all to do with the DEF quality poor message. For that they followed their playbook and told me that the DEF fluid I bought at the advanced auto store is bad and I need to use AC delco fluid. They drained flushed and tested the fluid and charged me 45 bucks for their fluid. I picked up the car and said "see you tomorrow" sure enough 30 miles later the message came back on. I took it back and got a loaner car. Now they will likely change the whole DEF tank and pump but that is not the problem either. Then I suppose they will try to blame it on bad fuel. When they exhaust all the options that don't involve them thinking, they might actually do something to fix the car like reprogram the computer to raise the tolerances .
 
#17 ·
There's so little service history on the emissions control system of this engine that it's almost a process of elimination from the service technician's perspective. So the first thing they do is try to address the variables that aren't under their immediate control like DEF and fuel quality. One of the realities of being an early adopter.

But please keep us informed and don't loose faith.
 
#18 ·
True. It is good judgement to rule out the simple stuff first but to say that the DEF fluid at the wal mart is any different than the DEF fluid at the GM dealer is a bit much to swallow. DEF is just Urea and water. Nothing magical or mystical about it and this is a common problem on the diesel silverados too so they should be better equipped to handle it. Currently driving a cruze with 400 miles on it so I should be happy about that.
 
#20 ·
Definitely keep us posted
 
#21 ·
Still in the shop. They changed the downstream NOX sensor. That didn't solve the problem either. They are scratching their heads now. They will probably just carpet bomb the problem with a whole new exhaust system. I think the the system is just not capable of achieving the levels it is trying to get. ULSD is 15 PPM sulfur and the system is trying to make it even lower. How can anything be that accurate ? If you get a bad tank of diesel that has 20 parts per million of sulfur the system may not be able to handle it. Who knows for sure ? Not me and unfortunately not GM. The emission systems are the weak link to the modern diesels.
 
#22 ·
Update. Got some encouraging news. The dealer says they removed the DEF injector and the injector nozzle was clogged and the spray pattern was insufficient. This is a plausible explanation for the exhaust fluid quality poor message. DEF fluid does get hard an crusty when it dries and the car sat unused in the body shop for 2 weeks after the encounter with the deer. I notice the white crud around the fill port after it dries up. They are installing the part tomorrow then they have to test it.
 
#23 ·
nice.

wouldve been nicer for them to have checked def flow already

if the conversion isnt happening, you gotta eliminate the easy, def quality and def flow...if those are good your box is dead, on our trucks thats 10grand

flow is easy to test, pump into a container, so many ml's per min

if flow is not good, check the pump, metering valve, def air regulator, plv
 
#24 ·
Failed again. I picked up the car after they changed the DEF injector. They claimed they test drove the car but the message came on 30 miles later same as always. took it back at got the gas engine cruze loaner back. They think they are doing me a favor giving me a car that gets 10 miles less per gallon
 
#25 ·
Well, at least the loaner won't throw a P24C6 code. :1poke:
 
#26 ·
Ha, too right. Its times like this when the cheap little gasser looks allot better. But I forget all to fast when I am getting 46 MPG. Hope it gets sorted out soon. The car ran for 47,000 miles with no trouble. Hopefully I can go at least another year without problems.
 
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