On the passenger side rear of the head cover there is a small unused bolt hole.
The SM doesn't show or describe what it might be used for. The hole is threaded so maybe a location for some part of previous models? I have an '06. TIA

 

I don't have my car around so I cant check, but are you sure its not for a jacking bolt? If its just a threaded hole that bottoms out on the top of the head then it likely is.

 

That occured to me. A bolt hole that might be used for a engine hoist but, I would also think that there would be at least two if this were the case and the bolt would be larger. Also it may be a bracket mounting point for something else that didn't come with the 2006+.
Anyone with an 06up please look at your car and note if anything is mounted in this hole.

 

No I dont mean that. Say you have two parts that are bolted together they can get pretty stuck, so you get a jacking screw which is usually the same thread size as the bolts holding them together so when you take all the bolts out you then screw one of them into this jacking bolt hole and as you tighten it the bolt pushes the two apart (bolt threads into one side then hits the surface of other). Usually you would have two of these on opposing sides to seperate the two items evenly. Might not be it, but FYI thats what a jacking bolt is. ^^

 

Yes I see what you mean and perhaps that is the answer. One bolt may be enough to break it loose.