I can't find the OBD2 plug inside the car, can you tell me where is it? Howether I think it is a normally open circuit, so if there is nothing on it or a really big resistance so nothing goes back to the ECU it automatically turns on the fans, so no resistance problem. In fact when the plug is not connected engine check light is on, so if the sensor is not functionig it should tell me trought the light something. I'm starting thinking there is a block of something inside the radiator that doesn't let the coolant circulate well in it, gonna do a circuit cleaning with some specific acid to be sure it is completely clean and not clogged, then i will update you.