Don't think you can check but may be wrong.If you are after assurance of reliability then, if you have never had coilpack issues,it may be a good idea to change all 4 and use 1 of the old ones as a backup(put it in the spare wheel well)
 
does a failed coilpak bring up an error about a cylinder misfire? i had 2 errors about cylinder 2 misfire,so swapped the 2nd coilpack...
 
Have downloaded vag com, just sorting out a cable now.
Local garage put it on their diagnostic machine on Friday as it was doing it in the morning but didn't do it again until today! They couldn't find anything wrong!
 
My revs ever so slightly (I mean a midgies di*k slightly) rise & fall when stood still, is this a coilpack on the way out or just another Leon fault ? :shrug: