Catalin, They are software locked so they will all “expire” even if you solder a new carbon monoxide sensor. I never ended up doing because the software would think it expired regardless of whether the co sensor was working or not.
I had this unit since 2012 at it worked without any issues. I never ran the cleaning cycle in all these years - there was a considerable amount of bacteria growth in the reservoir when I started getting these F3 errors… Now I ran it with hydrogen peroxide for 48 hours and it looks really clean. I know the pump works because on 117 HEAT it heats up the entire pad. However on COLD it still gives me this F3 error. The big fan at the top seems to never start now (although it worked fine when I started getting this error). It cools fine up until 72-71 but once it reaches that point it gets too hot and gives out that error.
One of my tubes completely broke. I managed to find a drinking straw that perfectly matches the diameter of the tube. I inserted the broken tube into each side of the straw - used some silicone but I’m sure it would’ve worked without it because of how snug the straw was. done!