Had a 2018 Sierra 2500 for a loaner while my 1500 was having warranty work done. We got a couple 0 degree days here in St Louis during the polar vortex and the 2500 went into limp mode and wouldn't allow me to go above 25 mph. CEL came on and a message popped up "Reduced Engine Power". I was 30 miles from the dealer that loaned it to me and they sent someone out and gave me a 2019 Silverado 1500. Next day they towed the 2500 back and found the diesel fuel had "gelled" from the cold temps.
Curious, is this common in diesels? I let it warm up for at least 5 minutes before driving as I know diesels need a little more warm up time than gas engines. How could it idle and drive up to 25 mph with the fuel "gelled" as the dealer put it? Didn't shake or sputter, just had the rpm limiter kick in at 25 mph.