ECT 2
WARNING: This page is about a different car, the 2015 Jaguar XK, 2014 Jaguar XK, 2013 Jaguar XK, and 2012 Jaguar XK. However, it is still accessible from the selected car via links, so may be relevant.
ECT 2 is installed in the lower hose connector which attaches to the bottom of the thermostat. The input from this sensor is used for OBD (onboard diagnostic) 2 diagnostics and, in conjunction with the input from ECT 1, to confirm that the thermostat is functional.