what is engine code p0405

What is your question?

i have engine management light on the dash iv cleared the codes and about half an hour later the light is back on with the code p0405 iv been told its the EGR unit so iv replaced the unit with a new EGR unit and the code came's back after driving 15 to 30 minutes there seems no lose in performance and no hisses bangs or weird noises

What makes this problem better or worse?

nothing

How long has your 2008 Jaguar X-Type had this problem?

quite a few months now