Suburban Diesel QDC Reset: Fix for Rough Running?

Had a similar issue on my 2019 Tahoe diesel. The symptoms matched exactly, rough idle and CEL light. After checking the fuel injection system, my mechanic found a faulty injector that was messing with the airflow sensors and overall engine performance. The fix involved replacing one injection valve and doing a complete compensation adjustment on the fuel injection system. Total repair came to 515 for parts and labor. Once fixed, fuel economy improved significantly and the rough running completely disappeared. Before suggesting specific fixes, could you share: Current mileage? Any recent fuel system maintenance? Any other warning lights besides CEL? Does it run worse when cold or hot? These details would help nail down if you're dealing with the same injector issue I had.

Thanks for the detailed response. Current mileage is 81303 KM and last service was about 2 months ago, just routine maintenance. No other warning lights besides the CEL. The engine definitely runs rougher when cold, seems to smooth out a bit after warming up but still not great. The fuel injection symptoms you described sound spot-on to what I'm experiencing. My fuel economy has taken a noticeable hit lately too. Interesting that you mention the airflow sensors, I've noticed a slight hesitation on acceleration that could be related to that. That repair cost actually sounds reasonable if it sorts out the issue completely. Did the system reset and compensation adjustment hold up long-term after your repair?

Thanks for those extra details. The symptoms you're describing are nearly identical to what I experienced, especially that cold-start roughness and the hesitation during acceleration. Mine started showing these exact signs around 79000 KM. After getting the injector replaced and compensation adjustment done, the fix has held up perfectly for over 25000 KM now. The onboard diagnostics haven't shown any drift compensation issues since. My fuel economy went from terrible back to normal within a few tanks of fuel. One thing I noticed post-repair was how much smoother the cold starts became. The car sensors now read correctly, and the fuel injection system maintains proper pressure without any compensation errors. Before the fix, my car would sometimes need multiple attempts to start cleanly in cold weather, that's completely gone now. Quick tip: while getting it fixed, have them check all the other injectors too. My mechanic spotted early wear on another one during the repair. Catching that early saved me from another potential failure down the road. Makes sense to get it checked soon before it potentially causes more issues with the fuel system. Those initial symptoms can snowball if left unchecked.

Thanks for the comprehensive follow-up! Really appreciate all those details about the long-term reliability of the fix. Hearing that your repair has held up for 25000 KM without any drift compensation issues is exactly what I needed to know. Going to book it in next week to get those injectors checked and the compensation adjustment done. The cold start issues are becoming more annoying, and I don't want to risk damaging the fuel system further. The car sensors are probably giving false readings at this point based on what you've described. Smart suggestion about checking all injectors while they're at it. Will definitely have them do a complete inspection of the fuel injection system. If the repair cost stays around what you paid and sorts out both the fuel economy and rough running issues, it'll be worth every penny. Your experience has given me a much clearer picture of what I'm dealing with. Will update once I get it sorted, might help someone else who runs into similar airflow sensors and injection system problems down the line.