If you have run full system diagnostics from f12 and the same error is displayed then you are probably looking at a bad fan.
Cpu fan failure dell inspiron.
Your dell pc may contain several fans to keep the internal components cool.
Lint and dust accumulation prevents air from flowing around the cooling fins and causes the fan to work harder.
Least expensive way is to replace the fan yourself.
The fan you need will depend on your graphics type integrated or amd.
Assuming you have the original dell fan it would appear the electronics in the fan have failed even though the fan is working.
Locations that charge a flat rate for the job.
Most expensive will be dell or geek squad etc.
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.
Next is a reputable local repair shop that charges by time not by the job.
Inspiron 5559 out of warranty cpu fan failure.