Steve- In my 930 I had a similar problem. In the GT3 I think it is called coolant regulator. I'm not sure if its a spring like in the old thermostat that can get stuck from grit / heat etc. Maybe a temperature sensor of sort if electrical...Our wire harnesses are getting old.

 

It went out when I restarted and hasn't come on since. As long as I know its nothing major its all good .