Temperature gauge doesn't work all the time 1999 1.3 Corolla

[Cunch]

Hello,

I recently bought a 1999 corolla and since I have bought it the temperature gauge on the cluster will only work the very odd time. If it does work it won't work for long. Not sure if it has much relevance but to this issue but when I turn the heating on when the gauge is not working the air coming out will be hot. 

From a bit of research it seems it could be the thermostat stuck open or the coolant temperature sensor. I think it could be the coolant temperature sensor but wouldn't know.

Anybody have an idea?

[oldcodger]

Hi,

If you can get hot air out of the vents, then doubt the thermostat is the real problem,  even if its stuck open it will just take a lot longer to get up to a reasonable temperature.

If it was stuck shut, then you would get hot air from the vents very quickly and the engine would rapidly overheat.

Assume the coolant level is correct ?

It sounds more like a faulty sensor , gauge or the wiring and connectors.

To check them you need at least a multimeter etc - is that your thing ?

Otherwise just changing the sensor might be the easier  way, seems they are not that expensive  from the usual big suppliers like ECP or Micks etc