Second time in less than 4000 miles, I threw the same code/CEL on my 19 Z. The first time was at 700 miles in freeway traffic, gentile throttle for over 2 miles. This time I threw it after cruising a mile of switch-backs, downhill. The environment was light throttle, heavy braking. Obviously, this setup is very sensitive to light throttle. I had it reset by Chevy today. I'll keep you uodates. Here are deets on the code: Onstar identified the source as ECM - Engine System - P2098: The Emissions System is not performing as expected. An issue has been detected in the Exhaust Emissions System which monitors and controls exhaust gases released into the air from the engine.