Alpha Romeo 156 JTD Refrigerant Sensor

Well, I have problems with the thermostat again or rather with the happy sensor. The one I put in the end was the old one but this no longer marks me correctly, it reaches 80º and lowers to 75º and remains in those margins, before changing the thermostat I have preferred to try to change the sensor, and the with the new one is passed from 90º circulating 1 km and does not jump the ventilator. In relief I put the heating and it is stuck in 90º, but when I go out. I do not know what to do it just, I have to leave it with the plug removed if it will have air and the liquid does not touch the sensor. Thanks in advance.

Solved, buy the sensor of origin and already perfect brand, you have to be careful with the manufacturers who want to make copies and make them like the ass, well thanks for the great help