My 2015 Sierra Denali 12,000 miles. DIC came up indicating I was less than 100 miles to restricted speed, fill DEF. Took it to dealer for refill, guy filled it, wouldn't clear message, checked codes, showed something else is wrong, tech determined truck needs new catalytic converter. Waiting on part, 12 days from Canada, and GM Engineering is asking why. Anyone else seen this? Will update as I hear more.