To be honest i dont think this is just a Citroen problem although it may be more prevalent with them due to their "quirkiness" as percieved by the general public
Im only 42 but i can remember being at school in the early 80's when computers (BBC/ZX81/Oric/Commodore) were becoming more available and i did take a passing interest but only as a pastime
At the time i had a Ford Cortina MK2 and can remember changing/replacing the piston rings and big ends/reseating the valves(got loads of splinters

)with the help of my Dad and the car was off the road for 36 hours
Nowadays i think we live in a throw away society where everything is electronically controlled and unless you have the "expertise" to do the job yourself(self belief

) then you trust the "experts"
A little knowledge goes a long way but i think the younger mechanics of today have never been brought up to "feel" whats wrong with a car they just plug it in and get a result,they dont have the savvy to question the result with any degree of logic ie the original post.....computer says fans not working...replace ...not find out why they are not working
Sorry if this is a bit of a rant but my mechanical/electrical skills are very limited(HGV Driver dont get paid to think just drive

) but just an honest opinion
Colin