Electric Thermostat
WARNING: This page is about a different car, the 2019 Jaguar XJ and 2018 Jaguar XJ. However, it is still accessible from the selected car via links, so may be relevant.
A resistance heater pin assembled within the wax element allows electrical input to heat the wax. By also raising the standard wax temperature the engine runs generally hotter during light load and low speed cycles, thus reducing friction in the engine and improving combustion in the cylinders, both saving fuel consumption. The electronic heater element then is used to open the thermostat valve, by melting the wax, in the higher load and speed points to protect the engine from thermal overload.