Conditions for Setting the DTC
WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The actual ECT is not within 10°C (18°F) of the calculated ECT after approximately 8 minutes, which depends on the amount of air flow into the engine after start-up.