There's two coolant temperature sensors on the engine: one for the instrument panel gauge (located on early cars to the rear of the cylinder head behind the thermostat, and on later cars located in the thermostat) and another for the ECU (on the thermostat). That's why some thermostats have space for two sensors.
The oil temperature sensor is located at the bottom of the sump, on the offside/driver's side (RHD cars) below the crank pulley and drive belts.
1996 Portofino 20vt & 2000 Pearl White Plus
1985½ & 2016 2017 Fiat 124 Spider + XF Sportbrake