Here are the requirements to turn the light on and set the code. A predetermined amount of engine run time(programmed into the engine calibration) and a corresponding amount of air flow has been used by the engine while running. At that predetermined time the engine coolant temperature must be at least 80°C (176°F). If these conditions have not been met together, then the light will come on and set the code. The engine coolant temperature sensor is a three wire connector with org/black, dk green, and a yellow wire so you will know you have the correct sensor. Also look at the intake temp sensor along with the mass air flow sensor. I think that you have an upstream problem and not a converter/ down stream problem. Did you change the thermostat first? If not, then I would change it now. Additional thought. What did you use to install the coolant sensor. If teflon tape, remove and use pipe sealant with teflon. It is a Loctite product that you can buy at auto parts stores.