SPN 4364 FMI 18?

[jimeneztrans84]

(05-12-2017 )JMBT Wrote:  Jimeneztrans84, also check the simple stuff. Mine has thrown this code often since new. It can be, and I would say is often, set by poor quality DEF fluid. If you have no other codes. I would first check for leaks, use the DEF pressurizing test on insite, then get under and look for leaks. Then replace the DEF pump filter if it has been in longer then 50K. Then unplug both NOX sensors and reseat them with a little di-electric grease. Then clear the code. If it comes back, which mine never has after the above, then pull and inspect the decomposition tube for deposits, and look into replacing the nox sensor or sensors.
4364 18 is such a BS code quickserve even says "do not replace parts because of it unless other codes are present"
If connected to insite during a regen and both sensors are reading stable, I would leave them be. When one goes bad it will usually throw its own code. I have replaced the in 3 times and the out twice in 600K.

That's the only code I get here and there. I will reset the code and it comes back 1 or 2 weeks later always when I'm climbing steep grade... no power loss, I replaced the def filter about 50k or so, might change it out again...start with the cheapest parts. I replaced the inlet nox sensor about 75k miles ago. I need to inspect the def injector and scr can... will be changing out filter tmrw....

[JMBT]

Well it sounds like you are on the right track! I had this code so often I threatened to buy a DEF refractometer, online about $50, but i haven't. Even buying DEF in the jug there is no way to know if it has reached it's shelf life of one year! Yeah, that's right it only has a shelf life of 1 year, then it goes bad. It wouldn't surprise me if the truck stops dump all their old DEF from the jugs into their bulk tank! I found the best way to keep that code at bay was to top off the DEF tank at every fuel stop, in an attempt to diluted any poor quality fluid I may have gotten. And always clean the nozzle off with a paper towel before filling your tank. Even the crystals that form on the nozzle can contaminate your system.

[JMBT]

Oh yeah, luckily Insite fault tree says for the CM2250 that code alone "has no effect on performance."

[jimeneztrans84]

So should I not worry about this code?

[JMBT]

I freaked out about it the first few times, but I would go down the fault tree on insite and check everything it said to and not find any problems, so I would delete it and move on. My advise is to do all that was mentioned above to put your mind at ease that there is not a real issue. Check everything thoroughly and if there is a real issue you will find it, if not then delete. If no issues are found try buying your DEF fluid at a different location for awhile.. Just my two cents.
As a side note they do say SCR cans wear out inside. I have heard everything from 400-800K. However Cummins says not to replace one based on 4364 18 alone, so I am guessing there is another code it would throw in conjunction with that one?
My truck threw that code the first time with 46,000 miles, practically new.

[jimeneztrans84]

Just got code for injector behind turbo. You think this code might be causing the other code? Only getting this code now. Not both at the same time....

[JMBT]

Yes, I think that sensor failing could very possibly have been causing the efficiency code.

[jimeneztrans84]

Going to change today and check readings on nox sensors

[jimeneztrans84]

Did a force regen and everything looked good
. Nox outlet was lower than inlet. No codes. Maybe it just needed a good forced regen since I'm running local now.