I have been getting some grey fault codes on my 451 related to the EGR and wastegate solenoids so I took the EGR solenoid off to poke it about a bit and discovered that the air inlet that releases the vacuum was completely blocked with soot.

This is probably a fault that is going to develop on the Smart CDIs. I think the wastegate solenoid is the same device so that is probably the same but much more difficult to remove.