I assume you mean coolant temperature sensor, not thermostat which is a completely different thing. Expect a sensor resistance of around 3kohms when the engine is cold, falling to about 200ohms when it's hot.

No, definitely the thermostat. Looking at the engine there is the coolant sensor just above the thermostat and that is showing the correct temperature on the dash - it sits quite happily at 90°C until the car is at standstill for some time and it will rise slightly.

The thermostat has an electrical connection, which I understand is a heating element, but I would not swear to it. I would expect something a lot less than the 230kOhms I have measured if it is an element

Heating element in the stat housing should be around 15 ohms. There is also a second coolant temp sensor in the lower rad hose. Is there water flow across the rad?

elekie&a/c doctor thanks for the reply.

15 Ohms sounds more like what I expected, so it looks like a faulty stat.

I would have to check the water flow across the rad. Would there be any issue as the engine temperature looks OK?

Is there anything I need to check on the other coolant temperature sensor? Which one provides the information to the dash temperature gauge do you know?

Thanks

Edited by Deryck Tintagel on 22/02/2017 at 09:57