Hi I have been having trouble with my new (used) c-max. It has done 100,000 miles and I have had it for about 1 month and in the last couple of weeks it has been juddering going along and producing lots of black smoke. A diagnostic check shows error code P1412 EGR Valve and P1609 Malfunction Indicator. Could the first code be causing the other codes and when reading the other posts on the site is it worth changing the EGR valve as this doesn't seem to have helped in other cases. Any advice on my best way forward would be much appreciated.