My 2016 Sierra 3500 seems to have everyone stumped. It has 275000 miles on the original engine. It’s on its 3rd transmission. The truck had been running super solid but then about a month ago check engine light came on and was running a little rough. Pulled code for bad catalytic converter… so we changed those along with all oxygen sensors…. Truck running good for about a week and then had a really rough shift on acceleration, check engine light again but no other symptoms. Ten minutes after check engine light comes on truck turns off going 49mph and will not restart… it would crank but not turn over. Had it towed to the dealership, they said ECM failed…. Weird but ok, they replace that… then tell me there is a code for crank shaft sensor…. More weird but ok.. I asked why both would fail at the same time but they couldn’t tell me….. so they change crankshaft sensor then call me to say it’s idling high and engine is reving up and down and that I should service the throttle body… at that point I bailed on the dealership and drove it home as is. The truck has been burning oil rather quickly as well. I have it home now and I guess it’s technically drivable but it sounds horrible, super rough and shifting is rough…… any ideas?!? Help!
