There is no code to reset if it's your thermostat. You can reset the car yourself, but you will probably find that the hot engine comes on again. It's around $25 for the part. It's something that can be done at home, if you're willing to put the effort into it. There's a ton of threads in here about the bad thermostat in the STS-V. All the same symptoms as yourself and almost all of us had a thermostat go bad.OK I get that I need a T-Stat . The car has sat for over a day and when I start it up for the first time the code a and fans are on . the engine is clearly cold. is there a code I need to reset?