Do you guys think it needs a software upgrade?

the temperature gauge does not behaves normally sometimes it stays all the way to the bottom and sometimes it works and i just change the temperature sensor and is doing the same thing and the engine does not overheats because i dont see the reservoir boil

i have a 1999 s80 t6 and my fan only turns on when the car is turn off, i change the cooling temperature sensor, termostat, and the radiator fan ,temperature sensor reaches half way and the fan won't turn on. what else could it be so the fan would turn on and it wont overheat. these are the codes th...