Just fitted brand new radiator 19.jtd elx air conditioning just started it up bleed it and the engine warning light on says engine ctrl contact garage the only thing I have done is disconnect the battery and removed air box for access unplugged sensor on air box

Assuming it's directly related to the work that's just been done ...

Check that the connection on the airbox sensor that you unplugged is good and that the wires to it aren't damaged.

Also check that the airbox pipes mentioned in this post are all connected properly, secure with no splits -

https://www.fiatforum.com/multipla/426493-engine-control-faulty-again.html

And the other post
https://www.fiatforum.com/multipla/480037-engine-crtl-faulty.html