Poor DEF quality no check engine light

[Rawze]

It could be poor quality def fluid.. which case, the tank needs to be flushed and new def fluid put in .. however ...

The def quality sensors are also notorious for going bad. - The problem is when they do, there are no replacements to be found anywhere.. as they have been known to often be on back-order for 6 months to a year+.


(for people with a warranty on their truck and emissions systems still)...
The problem is so bad that cummins themselves has a program update/patch to allow someone to drive if it is only that one bad sensor and the CEL light staying on, without it shutting the whole truck down. So if a person is near a stelaers$it and it is still has an emissions system warranty on the truck that is active, then that is one possible place you could go to maybe have it dealt with. The trouble is that someone then has to try not to get ripped off for some bogus shop fees or other things the stealers$it might want to claim, essentially ripping you off in the process for that ehemm .. so-called ... "free" repair.

(for people with no more truck warranty)...
Otherwise if there is no warranty and a replacement sensor is nowhere to be found ... then you might very well be looking at having the programming that you already have, 'patched' so that it does not shut down for this problem while waiting for a new sensor the next year and a half if it is one of those parts on the endangered species list. Some of those DQS sensors are sometimes fetching more than $3,000+ for just a used one out of a junk yard, due to the over-demand. Copying the program out of the ecm and e-mailing it to one of the recommended people on here, or myself, it can be patch to allow the truck not to shut down, or whatever other course of action, etc.