A modern Beijing Sonata car with a mileage of about 56 thousand KM. The car is a 6 - cylinder automatic transmission model. Car owners reflect: when the car is high speed, when the speed of more than 130km/h, the engine coolant thermometer will be indicated to 110 degrees, low speed driving temperature of about 90 degrees. Fault diagnosis: the car changed the radiator in the summer because of the accident and changed the radiator. As the temperature rises, it is found that the temperature of the coolant is too high at high speed. Because the high speed is too high, the test car is not very convenient, so the thermostat is replaced by the previous experience and the radiator is cleaned, after several days' driving test. The failure is still not ruled out.