Frank 2021

[2021 GMC Sierra 1500 AT4 - 5.3L ECOTEC3 V8 W/DFM - currently @ ~3676 miles - purchase NEW this past May 30, 2021] After the first CEL occurring within two weeks of purchase (see previous comment on page 1 blaming old winter grade fuel) I have driven this truck all summer long (having put premium gas in once or twice shortly after first servicing) with several trips to the beach (including 4wd on the beach) no issues ... but a second CEL occurred two weeks ago (first week of Sept) after a long idle in line for a child pickup after school. It disappeared on it's own a day or two later. Just had it serviced along with another issue where my passenger window would roll back down after I rolled it up. (Sidenote: I did get a base model 2018 Silverado as a loaner but I ended up getting the truck back same day. - Better loaners were promised me by the sales manager after some dealer errors on the purchase day. Not sure that Silverado qualifies, but I digress.) Written on the service order was the following: "... DTC P0300 with cylinder 1 & 6 misfire counter history at 130 and 232 misfire counter and number of other cylinder with small amount of misfire counter history" Since the CEL was no longer on they also documented this: "No misfire detected ... Recommend reprogram ECM with latest calibration and relearn crankshaft variation Doc ID#5869744" I don't seem to be getting the quite the same feedback from the technicians as some of the others here, not sure if that means they are being coached to not say it but I guess I'll see how long this "fix" will last.

Yes, same exact vehicle (2021 GMC 1500 AT4) - 281 miles on it, not even two weeks old. Check engine light was on and I took it in. Initial diagnosis was misfiring - waiting to hear more. I heard a ticking sound on the test drive also - unsure if that is related though seemed to be mentioned on another website. Frustrated beyond belief that a new vehicle (that’s basically a 3rd gen) would be going thru this. Bought it for a family trip to & on the beach in less than a week and been customizing it with racks, etc. First GMC purchase and I’m not feeling confident about the brand at all now. FYI - Couple of other sites referencing this issue: https://gm-techlink.com/?p=13855 https://gm-techlink.com/?p=14363 Hoping my techs do their research and they can fix it fast, I’ll be furious if I have to get a rental for the trip. Hope they figure yours out fast too. No new vehicle purchaser should have to go thru this.