New 2500 - Engine Misfire and CEL

ScenicView · January 16, 2018

I have a new Sierra 2500 6.0 V8 truck with 2300 miles on it. This morning I remote started it and it cut off right away. When I manually started it the CEL was on. I brought it to the dealer and they wrote the following: "Customer states check engine light is on. Scanned and found code P0300 - engine misfire detected (history). Checked misfire data and most cylinders had a few misfires as well as cylinder 7 having the most with a few hundred-all history. Cleared code and misfire data then test drove. Scanned again after test drive and no code or any misfires found (current or history). No correction at this time."

The service advisor said that these trucks can misfire when cold started. It was probably 15 degrees out overnight, but I had no problems that I know of when it was -9 (real temp) so 15 is like a heat wave.

Should I be concerned about this on a new truck?

mjm-1957 · January 17, 2018

I am a mechanic in a Gmc-Buick dealership and also happen to own a 2017 2500hd 6.0 and I can tell you that is not normal. Did you just fuel up before it was left overnight? The way those fuel rails sit in the intake manifold has the number 7 and 8 injectors catching all the sediment and crap in the fuel. I would keep a close eye on it. The misfiring can and will damage the cats.

carkhz316 · January 17, 2018

How cold is it where you are at? I have a '12 (same motor), and it has been -30* on and off for the last month. On those cold mornings, It'll sputter on like half the cylinders for a couple seconds and then it's fine. It's never illuminated the check engine light, and truck runs flawless the rest of the time, but the extreme cold certainly makes it run goofy sometimes.