I know this is a very common issue on these and there has to be a kazillion posts on here about it... by my search returned such a diverse array of results with different threads and down the rabbit hole I went coming out more confused and bewildered than before I did the search. I have a 2012 6.6 (this is in a transit bus, an Eldorado conversion) and I am getting the dreaded limp mode on account of DEF error. I have seen two prominent culprits rise to the top (9th injector and NOX sensor) of the list and am wanting feedback. I know I should do a more in depth scan (which I plan on doing) to get more specific data on what is going on, but ahead of running that scan, I am wanting to know by consensus how common it is for either the 9th injector or NOX sensor failure/fouling is the ultimate cause of this issue. Lastly, I am wanting to know how common it is for the DEF itself to become clogged with soot and causing these faults. Thanks in advance.
soundquest
LML's are notorious for having a failed DEF tank heater. I've had 3 replaced now. Even the quality of the DEF can trip a service code.
Anyhow you need to either get the service codes yourself or take it to someone to service. On the emissions it could just about be any guess what the issue is.
Some of my experiences
3 failed DEF tank heaters
failed NOX sensor(s)
failed pressure switch for DPF
poor DEF quality (lower tank and clean out)
9th injector failed
GM needs a DIC message that says "Hahaha you're F**ked Again"
Anyhow you need to either get the service codes yourself or take it to someone to service. On the emissions it could just about be any guess what the issue is.
Some of my experiences
3 failed DEF tank heaters
failed NOX sensor(s)
failed pressure switch for DPF
poor DEF quality (lower tank and clean out)
9th injector failed
GM needs a DIC message that says "Hahaha you're F**ked Again"
Also after a CP3 conversion was done the regen dosing line for the 9th injector was blocked. The tech threw away the new line before anyone could determine what caused the blockage. Could have been a packing peanut, manufacture defect, who knows. Anyhow the blocked line put it into limp mode. Not enough fuel for the 9th injector to regen.
If you have no code reader... take it to Auto Zone or O'Reilly's and they can get it for you. Possibly other auto parts stores will do that for free.
Thanks for all of the great replies. I thought there were no replies on this post (spam filter sent all notifications to junk folder) but much to my surprise -- all this great info has been sitting right here the entire time, thanks to all your replies. By way of clarification, I found out this is actually an LGH (not LML like I was told). Officially, it is a Chevy Express 4500. Thought it might be important to include that detail, even though the LGH is close relatives to the LML. And the code I am getting is P2463 (diesel particulate filter restriction). My plan is to get the old DEF fluid out of there and put some high quality BLUE DEF PLATINUM in it and pull some numbers. I now have a very capable code reader that has the ability to tap into all the sensor data and even force a REGEN. I want to pull DPF pressure numbers first (and other data) to make sure there is not too much backpressure. If the numbers come back within range, I will then proceed to force a regen and let it run for an hour (fire extinguisher at the ready of course as this is being done in a field with weeds and shrubs and I am told the exhaust gets furnace-fire hot... like... Shadrach, Meshach, and Abednego HOT!). If forced regen is unsuccessful, then I will consider performing an in-situ full cleaning cycle using the lubromoly DPF clean kit... unless I am steered in a different direction by this forum. If things are really caked on in there... this will not work I realize. Worth a shot though. Thoughts? Any other advice?
At the truck stops, I suggest taking a paper towel or two and wiping off the tip of the dispenser. I've seen a few that were very dirty. You don't want that getting into your DEF system.
DEF fluid should have nothing to do with dpf restriction.
To me that would point to failed regen, either the truck isnt being run long enough to complete regen, or poor fuel cause the truck to not build enough heat during regen or both, could also be the 9th injector. Have you seen a 420 code. Thats thrown when truck does not reach over 1000 degrees to the dpf during regen. Does the truck roll white some for about a minute trying to start regen? With this system something as simple as getting fuel from a different source can sometimes solve the problem.
But im thinking your almost to the point the truck goes to speed limited mode then your SOL. Damn near need to bring the truck in to a shop if it goes to limp mode.
I had it before where the fuel tank had to dump do to fuel not producing enough heat for regen. Fresh fuel solve my issue.
To me that would point to failed regen, either the truck isnt being run long enough to complete regen, or poor fuel cause the truck to not build enough heat during regen or both, could also be the 9th injector. Have you seen a 420 code. Thats thrown when truck does not reach over 1000 degrees to the dpf during regen. Does the truck roll white some for about a minute trying to start regen? With this system something as simple as getting fuel from a different source can sometimes solve the problem.
But im thinking your almost to the point the truck goes to speed limited mode then your SOL. Damn near need to bring the truck in to a shop if it goes to limp mode.
I had it before where the fuel tank had to dump do to fuel not producing enough heat for regen. Fresh fuel solve my issue.
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