T595 Daytona Temperature Gauge Not Working Properly

Chuffed to bits to take out my 97 T595 for a test run following fitting of a replacement Gates thermostat and new temperature sensor. Runs really well but the temperature gauge only moves a fraction to just above cold and the engine management light is still stuck on.
Had a further check of the heat sensor and then ran it static for a while and the gauge crept up to the first graduation above cold which is where it used to sit. I had some coolant discharging from the expansion tank overflow, which is the system probably finding its level, but the fan did not kick in, so does this indicate the thermostat is not working? EM light still on, so is the solution to clear it with Tuneeco?

 

Thanks Iceman.
It has been stuck on ever since I was told I had a faulty thermostat and temperature sensor, but yes, I did disconnect the battery when replacing these. Three cycle method doesn't appear to be working so it looks like Tuneco and hopefully I will then see if I actually still have a fault and go from there. Jon