W210 E430 Error Code Query?

[Veridian]

Hi folks, a quick query - I know that one of my coil leads has broken down and needs replacing. Im thinking of replacing the whole lot - dunno whether to go genuine Merc at, I believe £20, a pop x16 - gulp! or to go aftermarket - any recommendations. Its done 120K miles so will be due a sparkplug change too.

But to my query itself - in the meantime I thought Id see if I could identify which cylinder had a possible misfire by bringing up the error codes and hopefuly spotting P0xxx. and changing the offending lead in short order. But all I get is Eb 1231 and then E FF. Any ideas what E FF means?.. and why cant I get any other error codes up?

Incidentally when lookign at the WIS on coil/plug replacement it doesnt seem to suggest that the leads themselves are separate to the coil itself. But Im sure they must be!