Difference between revisions of "Coolant Temperature Sensor (CTS)"

Revision as of 18:33, 10 May 2008

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.

Having discussed this with some Esprit owners, and with reference to their parts manual EMH.4, it turns out they have the same CTS thermistor characteristics {as well as the same ECM}. Their part number is A910E6928F and is available from SJ sportscars for ~12GBP whereas ours is closer to 50GBP! This is unhelpful though at the present time (2008) as they are on backorder and Lotus "can't find a replacement".

ESM did some research and found data for the Pontiac Fiero has the same CTS thermistor characteristics. Cross referencing with a US parts site Parts America gives several options for the 1988 Fiero CTS. This site is useful in that you can view a part and then see which vehicles it fits. The Fiero CTS is common with the Isuzu Impulse RS and Geo Storm (as suspected but I don't think it has been proven until now) and more importantly for UK owners, a car available in the UK - the Isuzu Trooper (1986-7 with 2.3l engine and 1992-2001 with 3.2l & 3.5l V6 engines) as originally suggested by ESM.

They have been sourced from Vauxhall for ~15GBP with the ACDelco part number 25036979.