Component Testing
WARNING: This page is about a different car, the 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
Measure and record the resistance of the ECT sensor at various ambient temperatures, then compare those measurements to the Temperature Versus Resistance (IAT 2) or Temperature Versus Resistance (ECT) or Temperature Versus Resistance (IAT 1) table.