Wife's 2018 se w/tech 4 motion v6 kept throwing cel but would go out before she could make it to the dealership. Been doing it for about 5k miles. Finally made it when it was still lit and was told she needs a new catalytic converter. Of course this is covered by warranty so there is no cost, but it seems like this can't possibly be the case. Can they "go bad" after only 15 - 20k?