Scotty, I have a 2016 GMC Sierra 1500 SLT Z71 with 63,000 Miles. My check Engine light came on flashed for a minute went back off. Took it into the dealership, they scanned it.. said I had a P300 Random Misfire and 88 Misfires on cylinder 5. They kept my truck for 9 days drove it for 100 Miles and could not get it to duplicate. The Manager in the service department told me 88 Misfires is on the low end and I should not be concerned with it, then told me they currently have one in the shop with 4,900 Misfires... It's under warranty till 110,000 Miles....I know your not high on GMC but I really like my truck..just has me concerned...Thanks...
Range of misfire also matters, if your car is not shaking during idle or you don't feel anything abnormal, then GMC might just have sensitive sensors and the vehicle is most likely ok. Technically tiny misfires occur during every ICE engine start up but is immediately corrected by the car's computer so idk. If the shop couldn't replicate the issue there is no harm in taking it to another to get a second opinion.
No matter what problem you have, the dealership can never seem to duplicate it and therefore will not fix it.
