Hey so my engine temp gauge isn't working just wondering if anyone knows the diagnostic steps to figure out what exactly is wrong.
I have a small coolant leak so I'd like to get it fixed soon

Check for error codes first by bridging the two ports in the diagnostic plug and checking the flashing check engine light.  It will tell you if there is a fault or a disconnected sender.
You can google to get the instructions for it.

Check the wire is connected to the gauge temp sender
Check the sender works (remove it and put it in water with a thermometer, raise the temperature and use a multimeter to check the values it gives)
If you've changed anything at the back of the gauge cluster, check those connections are all ok.
I guess the gauge itself could fail too but I'd say it's pretty unlikely.
This might help - http://mr2.neogruts.com/engine/engine.htm
 
They'd be my steps to test.

Has it just started the issue or was it always the case , e.g a new swap ?

Thanks for all that info

I honestly don't remember seeing it working since I got the car, but the previous owner told me it was definately working since he never drove it until it had warned up to about the 2nd bar atleast. So it has stopped in the past 6 months. I don't know how I didn't notice but I think I first noticed it about 4 months ago

Nothing recently has been done to the car to make it stop.

So lets breakdown a problem. You might want to give a bit more information first
What model car ?
N/A or Turbo ?
Is it a Turbo swap ?
If so what GEN ?
 
Its either not connected or its no good.
I bet it was never connected
You driven the last 4 months without a working gauge?
 
83420‑16040 around $60

I think I've got a used temperature gauge sender here if yours turns out to be faulty and you want a cheap fix.
 

92 GT-S with CT20B

Thank you I'll let you know if I need it

Highfive, I have the same car :)
 
Yeah check the connection, the wire from the sender is real easy to break or bend if anyone has removed that coolant neck thing next to the distributor.  Easier to get to than the cluster as well.

Connection or sensor