2012 Dodge Ram 6.7L Engine Fault Codes P014C, P014D, P0191, and P2BAC - Diagnosis and Repair Guidance

I own a 2012 Dodge Ram Mega Cab with a 6.7L diesel engine. Purchased in November 2016 with 59,000 miles on the odometer, it ran reliably until July 2023 (71,464 miles), when the check engine light activated and triggered fault codes P014C, P014D, P0191, and P2BAC. I took the truck to the dealer, who installed a wiring harness overlay based on a Dodge Technical Service Bulletin (TSB). The check engine light remained off for two weeks before returning on again at 72,322 miles. This time, the codes are P014C, P0-14D, P0191, and P2BAC. A different technician reviewed the issue and confirmed that codes P014C and P014D should be addressed first—though there is a long list of potential causes for these issues. I'm seeking advice on where to begin troubleshooting, as I’m not confident in diagnosing this myself. The mechanic I trust is a Ford specialist, though he knows me personally and has no bias. I acquired the truck because my 32-year-old son owned it and was tragically killed shortly after I purchased it—this vehicle holds deep personal significance for me. While I value keeping the truck, I firmly believe that persistent check engine lights indicate underlying issues that must be resolved. Any technical insights or troubleshooting steps would be greatly appreciated.