Hey Scotty a friend of mine just bought a 2021 Chevy Silverado 3500 and at just under 200 miles, it threw up check engine light. My cheap-o code reader retrieved a P026C code-Fuel Injection Quantity Lower Than Expected. The light keeps intermittently turning on and off so it isn't predictable as to when it will throw the code. He can go a couple of days with it off and then it will appear for the next day only to disappear the next. The dealer from which he bought it is telling him that they don't know what is causing it and how to fix it even after connecting the truck to their expensive computer. GM seems to be a bit confused as well since my friend contacted them directly and they do not have an answer. The repair shop says that there is a bulletin about this within Gm but no resolution. They just tell him to keep driving it and they'll get back to him. He likes to use the remote start feature, but it's a crapshoot that it will work since the feature will not work with the CE indicator on. When I check Google, I don't find much info on Silverados/Sierras with that code but I'm seeing in the RAM forums that the issue is injector related. Since there doesn't seem to be any performance or hesitation issues, I'm thinking either DEF or fuel injector sensor, but you'd think that would be an easy troubleshoot and fix for the dealer repair shop. What say you?
This seems probable, given that GM is acknowledging the problem, but WTF kind of QC allows new parts to be corroded so quickly:
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A number of fuel-related DTCs may be set on some 2017-2018 Silverado, Sierra; 2019-2021 Silverado 2500HD/3500HD, Sierra 2500HD/3500HD, and Silverado 4500HD/5500HD/6500HD models equipped with the 6.6L Duramax diesel engine (RPO L5P, L5D). DTCs set in the Engine Control Module (ECM) may include P0087, P0089, P0191, P026C, P026D, P1089, P163A, P163B, P2293, P228A, P228B, P228C, and/or P228D. The Check Engine MIL also may be illuminated.
These conditions may be caused by corrosion or damage at the fuel pressure sensor electrical connector. (Fig. 30) Inspect the connector for any damage. It may be necessary to use the terminal test kit with dielectric grease on it to drag each terminal a few times.
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https://gm-techlink.com/?p=14070
@geriscan: probably something I should have noted as well is that this truck was ordered from the factory. It wasn't sitting at the dealer for any amount of time. So if there's corrosion, that would be a HUGE red flag for me. I'll forward the link to him since there is a chance that he does have a bad/damaged sensor that could have passed during testing, but is failing intermittently. Thanks!
Scotty has a low opinion of contemporary GM quality: https://www.youtube.com/watch?v=jSdhh-4ZxXE
At under 200 miles, if the dealership can't/won't fix it, I would take it back and demand one that works!
Id throw the keys, the title, any receipts, loans lease or finance documentation over the front desk of the dealership and demand they go across the street to buy you a Toyota.
I'd start gathering documentation -- emails, conversations, etc. Find out what your state's lemon law is, and tell your friend to shape his documentation to meet the requirements of that law. Your friend may need to exercise the options it gives him.