I'll be the first to admit I don't know much about fuel injection and the computers that run them. I'm more of a Crane HI4 and S$S Carborator type of person.
That being said, I've noticed a drop off of my fuel economy, from 52 to 46 on the highway. I monitor this pretty close. I had changed the plugs from the Harley plugs to Autolite several thousand miles ago. I did a plug check and they were burning more chocolate than they were when the bike was new. I changed the plugs back to Harley plugs, put a new airfilter on it and went for a ride, 60 miles at 70 mph, with a burst to top end.
I pulled the plugs and the rear plug is chocolate, and the front is white-ish. That used to mean the front is running leaner (hotter) and the rear is running richer (cooler).
Whatcha think...Don't worry about it?
The bike is stone stock, no performance mods.

 

The engine check read on the odometer usually comes on if there is an emission problem, bad plugs, open exhaust, air intake. Check your plug wires. Poor insulation or a poor connection would cause discoloration.
Also, if you look up engine check light in this forum there is a set of proceedures using the punch button that will bring up any problems found by the ems system.
I have an 07 RKC not happy with the existing ems system. When cash available I plan on contacting fuelmoto for their rush jackpot, pc111, air intake. Good Luck.

 

rich in the rear isnt a bad thing it will keep the heat down some as long as your not fouling the plugg.maybe the rear 02 isnt reading right on.

 

The bike starts good, runs good, and there are no bells or whistles going off. I'll monitor it over the next few thousand miles and see what happens. Thanks for your replys. Al