2022 Check engine light

[50BMG]

I purchased new a 2022 GMC 1500 Denali Limited. Day one when I picked it up while driving home the check engine light came on. Called the dealership and they sent a ramp truck and back it went. After changing the oil and performing a fuel injector cleaning process they sent it back The cause according to the dealership was carbon had built up from it sitting? Two months later the check engine light came on again. Back to the dealership and was told it had over 20 misfire codes. The truck has 281 miles on the odometer. I was then told the wiring harness from the ECM had worn through and a replacement was ordered. Three months later the harness arrives. I drop the truck off at the dealership and on day two I receive a call from the service manger that it was not the wiring harness and the cause was carbon build up because I don't drive it enough. The truck has 281 miles on it. It is stored in a heated garage and I only use non ethanol 91 octane fuel. My question is how can carbon build up if the vehicle is not driven, no combustion is occurring if its sitting in a heated garage. Any thoughts? I contacted GMC support and they have been in short no help.

 

[ChadillacAT46.2]

I've heard and read they had a bad batch of fuel injectors in '22. If it's misfiring it's most likely the injectors and they know about it. Should be a TSB out on it as well. I agree it definitely should not have carbon build up if it's not being driven much (ie no combustion in the chamber going on if sitting) and no corrosion if sitting in a climate controlled garage.