Conditions for Setting the DTC

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The ECM detects that the actual engine coolant temperature is 11°C (20°F) colder than the calculated thermostat regulating temperature of 89°C (192°F) for greater than 10 seconds.
OR
The ECM detects that the engine coolant temperature is 11°C (20°F) colder than the calculated ECT for greater than 10 seconds.