If it's one unit, yes -- and since both fans have the same number of runtime hours, if one has failed the other likely will if not now, then shortly.

@ejn63​ Thank you so much for your answer. I am not sure if they are one unit or not. My laptop is Dell D15 5515. 

Another question please. If the problem in cpu fan only, should they change GPU fan and heatsink also?. The engineer told me that cpu, gpu and heatsink come as one unit. Thank you again for your help.

@Asmaa Y.​ 

It's common that they are one unit, but anything more definitive than that requires a piece of information you have not supplied -- what model Latitude?  5430, 5550, etc.?

@ejn63​ thank you for your help. D 15 5515. Dell 15 ryzen edition.

Dell G 15 ryzen edition 

@Asmaa Y.​ 

Moving post from Latitude to Inspiron forum.

Yes, the heatsink-fan assembly on that model is a single unit.

Also note that the part you need depends on the GPU you have.

https://www.parts-people.com/index.php?action=search&search=G15++5515+fan

Before you order anything, run the pre-boot diagnostics (tap F12 at power-on and pick Diagnostics) so you can see the exact fan error code — that confirms which fan the motherboard thinks has failed. Also check whether the laptop is still under warranty, since a failed fan is covered and replaced at no cost. And if the machine was opened recently, have the tech reseat the fan cable first — a loose or slightly unseated connector throws the very same fan error and it's a free fix.

@noahmitchell​ thank you for your reply. The laptop shows cpu fan failed. Yes the laptop has been opened recently. 

@ejn63​ I did not know that gpu is different in the same laptop model. Thank you.