The last few days my fan has been kicking in on short and long journeys.

I've checked oil. And coolant and all is ok

I've had it diagnosed nothing found

Fabia 1.2 diesel 2013

Diagnosed how and by whom?

Found a faulty egr valve code today on diagnostics machine

They said that would cause the dan to kick in as often as it is

Having new valve fitted next week

Hope there're right

A very expensive shot in the dark perhaps.

Do you have any warning lights showing on dashboard display? Also are there any other quirks or faults?

Engine management light does come on now and again

And I've noticed that fuel consumption has dropped over the last week

Only getting 45mpg

Sounds like it trying to regen frequently to me.