'CPU fan failed' after cleaning

[yueq]

I cleaned my CPU fan by blowing dust. But after cleaning it says 'CPU fan failed'. I can continue to run win7 by constantly press f2 key. OS loads perfectly but it seems that fan is running at full speed, very noise. I doubt the issue in the CPU fan sensor. Could any one give me some help? Thanks!

 

[WR2]

Why do you doubt it's the fan sensor? That's exactly what it sounds like.

Did you detach the CPU fan motherboard connector and hook it back up to the header the wrong way?