Failed temperature Gauge

[Kevster74]

Anyone know what would cause a Temperature Gauge to stop, or more importantly what i should look at to fix it?

[MidLifeCrisis]

Assume you are talking about the coolant temp gauge?
So, reasons for failure could be;
a) the temp sensor itself is dead
b) the wire from the sensor to the gauge is broken/disconnected/decomposing!
c) the gauge is dead
d) the power and/or ground connection to the gauge are disconnected

You don't mention which engine type you have?
On a petrol 1.9 df/dg the sensor is screwed into the water pump/thermostat bit - not sure on other types.
If you can locate the temp sensor, it should have a single wire going to it; if you disconnect the wire and ground it to the engine block (with the key turned in the ignition) the gauge should go to 'full hot' state (with the LED flashing). If this works then the sensor is the culprit.
If that doesn't work then the culprit is wire, gauge or gauge power.
Test this first then we can talk about testing the gauge directly ...

(fyi - problems with gauges are often blamed on bad earths - have you noticed any other 'odd' behavour? i.e. fuel gauge misreading, other warning lights not working etc etc - these could be an indication of a dodgy earth. Does the LED flash test sequence work when you first turn the key (i.e. does the LED flash for a few seconds then go out?))

[Kevster74]

Thanks

I have a Subaru EJ20 engine, the red light sequence is fine. Rest of gauges are working fine. Took clocks out and cleaned contact connector, was very dirty but still nothing.

[MidLifeCrisis]

Do you know where the temp sensor is on your engine so that you can try out the other test?

[Kevster74]

Yes, found it and for how cheap a sensor is going to try that, tried additional clock set and that didnt work. Cant imagine there is a sudden problem with wiring when nothing has changed.

Thanks for your help.

[Kevster74]

Problem solved!

firstly the spade connector on the sender had come off, also the wire into the back of the connector on the clock set had worked loose. both now tweaked and tight and working fine.