My oil temp gauge has decided to go to the max and stay there (ignition on or off).

Is this a faulty gauge or sensor?

Best way to test?

If I remove all wires to the gauge it will return to zero. If I reconnect the wires it stays at zero until I switch the ignition on, then it rises to max and stays there.

Cheers

 

if you remove the wire normally connected to the sensor you will probably find that the gauge will still go full scale deflection in the same manner. This would indicate the the temp sensor has gone open circuit and hence needs replacing.

Ground the wire to the engine and the gauge should then drop back to '0'

 

Cheers Scott, will give that a go.