I had this problem. Traced it to loose threaded alloy end caps on the spark plugs. The tiny sparks created confuse the ECU. I have found that they are hard to keep tight, but any time my light comes on I tighten them up and all is well. Causes rough running at low revs too.
Ditto on this. The screw-on nipples on most plugs will have a tendency to work loose with time. I remove them put on some Loctite and put them back on then crimp them HARD so they will not ever move. The warning lamp goes off and the engine runs smooth. Well, as smooth as a V-Twin ever gets!
