P026D code on LML just purchased

[Eac95z28]

Hey everyone! I have been a long time reader and have just purchased my first Duramax. It is a 2013 LML 3500hd DRW CCLB. The injectors, injector pump, all hoses, fuel lines, and seals, etc. were just replaced on it a few months ago. It was only driven maybe a few hundred miles with the new parts before I purchased it. This was all performed at a dealership. The problem I am having is that the CEL light was off when I bought it but has now illuminated on the way home. I pulled the DTC and it is P026D which points to (Injector High Mass Flow). I tried clearing it and after 1 drive cycle the CEL stays off but PCM has a pending code for P026D. On second drive cycle, the CEL comes on and stays on. From my research on here and scouring the internet, it looks like it might point to the injectors needing calibration. I haven't completed a balance rate test on it yet as I need the software to do that. Any ideas on an easy way to check the balance rates? Also is there an easy way to calibrate the injectors is that something specific a dealer has to do? Will the PCM calibrate itself after so many drive cycles? I have put around 500 miles on it since purchased last week. Other than the DTC the truck runs great with no hiccups or abnormal issues that I know of. On the way back I was getting about 18mpg on highway with average of 70mph and in town so far around 12 but it's winter and I have been letting it warm up and idle in the mornings. I'm not sure what the average mileage is for city/highway as this is new to me. The truck is also completely stock unmolested with full emissions, DPF, DEF, and everything. If you all have any ideas to help that would be greatly appreciated.

Thanks,

 

[DAVe3283]

If you just bought it from a dealer, I would call them and see if they are able to help. Since they just did a bunch of work, there should be some kind of warranty. I wouldn't make things hard on yourself, let them fix what they broke when they worked on it.

 

[Eac95z28]

Unfortunately I didn't buy it from a dealer. I bought it from a private seller that just had it serviced at a Cadillac dealer. And it's not close either so it wouldn't be feasible for me to take it back up there. Would I be able to take it to any GM dealer a local one of mine since the work was completed at a GM dealer? He did mention the parts should be covered for 12mo/12k but I dont't think that includes labor. Not only is that the main issue, but the AC lines were loose and weren't tightened back up and there is no freon in the system. I found this out after purchasing it and now I'm stuck with having a dealer do a complete vac, flush, and fill on it. Would the dealer be able to cover this also as the old dealer didn't finish that when putting things back together?