I had similar problem replacing my Doblo 1.9 EGR valve (£130 Europarts) , remove the battery and it case,un clip the large rubber Turbo input pipe,un bolt the EGR lower pipe clamp and remove the complete EGR unit with its lower insulated pipe.Then remove those two Allen key bolts on the bench you'll need a box of rubber gloves and a tin of carburettor cleaner plus an old tooth brush to clean inside the pipes and block opening its a ****y sticky job to clean properly ?.