Jlsprad77

I had the same problem with my 2021 Sierra 1500. It will show the flashing CEL about once a week for a few weeks, go off and then it went solid. I took it in and they said it was problem with the lifters, which seems pretty common with trucks built between like September of 2020 and March of 2021. They replaced the right bank of lifters, and gaskets and bolts and sealed it up again. Changed the oil and flushed and refilled the coolant. I got it back and it ran great for about 2 weeks, now just today the CEL came back on again. Incredibly frustrating. To have a brand new truck to have less than 3,000 miles on it and have this kind of major engine failures. I don't think it has anything to do with fuel, but poor quality parts. The service receipt said misfire on #4 cylinder due to failed intake lifter and bent push rod. I have always had F150's, and went with an almost $60K GMC this time and very disappointed. I hope you can get your issue resolved. I am heading back to the dealership again in the morning. Now they will probably replace the left bank of lifters.