Conditions for Setting the DTC: P2184
WARNING: This page is about a different car, the 2007 GMC Sierra, 2007 GMC Cab & Chassis Sierra, 2007 Chevrolet Silverado, and 2007 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects that the ECT Sensor 2 parameter is warmer than 149°C (300°F) for more than 15 seconds. This is equal to less than 0.065 volt on the ECT sensor 2 signal circuit as measured by the ECM.