Greetings Everyone,

I am returning here after being away for so long I couldn't even remember my old user name! Oh well - I think I'll live!

My trouble is with my 2013 Silverado 2500HD 4x4 (56k miles) with the LML Duramax triggering a DTC P0420. My dealer is not being very cooperative, essentially because they have only one diesel tech and he is, well, "cranky".

My contention is that this code is being set due to a failing indirect fuel injector (a.k.a. - the "9th injector") mainly because I can tell that for the first 5-10 minutes of steady driving it will try to regen but fail, after which the MIL comes on. I can tell it is trying to regen because the mpg will fall to 13, but when the regen fails and returns to normal operation the mpg climbs back to 23. This won't last - when the DPF fills up the truck will go into limp mode.

The dealer is saying that they won't do the work to replace the indirect injector (under the special extended warranty) because the P0420 code does not specifically state the indirect injector is bad. When I ask which code must be set before they WILL do the work they cannot answer because the TSB for this problem doesn't specify the code. Instead they want replace the catalytic converters to the tune of several thousands of dollars that I will have to pay myself and will not guarantee that will solve the problem - and I refuse to to throw new parts at it until something finally works without knowing what was wrong to begin with. That can get too expensive for me quickly.

So I guess my question is this: Is the P0420 directly indicative of a failing indirect injector, and where can I find official info from GM saying such?

Thanks for any and all help - Jon (FireCapt651)