Scenie II 1.5 DCI Loss of Power (Already Changed EGR Valve?)

Good Evening all,



My EGR valve has been gunked for a few months but unplugged it and has been driving fine,



however just recently the vehicle has very little power at under 3000 - 4000 rpms - its like the car just has no power till the turbo kicks in!



So I changed the egr valve today but still have the same issue?



Ran the codes and got P0409 - Exhaust Gas Recirculation sensor A ?



Any ideas or tests as to what this may be?



Thanks in advance