I have a 2004 Mk1 Focus 1.8 petrol. After a great deal of trouble , DTC code P0351 came up but replacing the coil , plugs and checking the connection to the coil and the HT leads has made no difference. The car still idles terribly with no power and seems like it's only firing on three cylinders whereas I'm sure it's actually firing on all 4 in reality.
My question is , if everything tested fine and new plugs and coil were fitted , what else could cause this particular fault code to display ?
Thanks in anticipation