Coolant Temperature Sensor (CTS)

Lotus part number A100E6373S is the Coolant Temperature Sensor (CTS) which reports the engine coolant temperature to the ECM. It consists of a thermistor in a sealed package which screws into the thermostat housing.

Thermistors are negative temperature coefficient devices and from the Lotus parts manual EMK.4, the Elan has the following characteristics:

Temp(°C) / Resistance(ohms)

100 / 185

70 / 450

38 / 1800

20 / 3400

4 / 7500

-7 / 13500

-18 / 25000

-40 / 100700

This matches a thermistor with characteristics of R0=2700 ohms and Beta=3977 such as this one for £1.42 but you'll need a package (~£50?) to put it in.