This is an extra safety feature that dell uses in case a fan does fail the user will see the failure and avoid potential harm to the pc cpu.
Cpu fan failure dell inspiron.
Desktop pcs have more than one fan processor cpu dedicated or discreet video card gpu power supply psu and one or more chassis case fans.
Most expensive will be dell or geek squad etc.
Locations that charge a flat rate for the job.
Assuming you have the original dell fan it would appear the electronics in the fan have failed even though the fan is working.
Next is a reputable local repair shop that charges by time not by the job.
Least expensive way is to replace the fan yourself.
Inspiron 5559 out of warranty cpu fan failure.
The fan you need will depend on your graphics type integrated or amd.
If the fan is not working then i have to assume the system is shutting down as the cpu will overheat.
If you have run full system diagnostics from f12 and the same error is displayed then you are probably looking at a bad fan.