Fiat grande punto 1.9 multijet starting problem

[Pribi]

Hello,
I own a fiat grande punto 1.9 multijet, 2006. Im writing here because i dont know what else to do about my problem. The car wont start when the engine isnt completely cold. In a -5°C weather and with cold engine it starts completely normal but then it neads at least 4h cool down time until it will start normally again. So even if the engine is a little bit warm it wont start. I changed the fuel pump, checked fuel flow, changed temperature sensor (because when it doesnt start it shows an error in which states that the cooling fluid temperature is too high), checked the battery (which is also new), checked the car with different diagnostics and everything seems to be fine jet it doesnt start when warm (if its very warm it starts normally, it doesnt start just when its half warm). When the car doesnt start, I pop the hood up, disconnect the temperature sensor and the car starts fine (u can hear the fuel pump pumping for longer when i disconnect the temp. sensor). I dont know what else to check so if anyone had the same problem i would appreciate the help.
Thank you in advance.