After getting my car tuned yesterday i got an engine coolant trouble code. In the tune he change the radiator fan settings to 195f on and 191f off because i have the mugen t-stat. I didnt let the car warm up all the way today. When i got about two miles down the road the code came up. Just wanted to know what the cause of this could be.

 

What code is it?

BTW, ditch that cold thermostat! Unless you need it as a bandaid from tracking in Arizona, or something, you're just wasting precious energy. It's better to let the heat push down on your pistons than pump it out the radiator.

 

The code was P0128 coolant thermostat(Coolant Temperature Below Thermostat Regulating Temperature).