I am getting a sharp infrequent skip at idle.
If its a coil pack problem, and my check engine light has NOT come n, can the auto zone code reader find it or do I need to wait til the light comes on, and how long will that be?

 

If its a coil pack dying slowly, the check engine light will not come on unless it misfires for a long sequence for the computer to detect. You would have to leave your car on with it in drive and your parking brake up and disconnect one by one. You will then find the one that is misfiring.

 

sometimes a minute goes by before the single skip

 

If it takes that long, then I would suggest you clean out your TB and IACV first before doing what I suggested first.

 

Yes, you have to wait for it to come on. How long you ask? You could be waiting days,weeks...months...who knows.

I believe only a Knock Sensor code can exist w/o triggering the CEL.

 

I know for sure the knock sensor will not trigger the CEL, but I'm not sure if it's the only one that can do that.

 

Does your light work? Check at start-up to see if it comes on for a second.

 

IIRC KS is a ghost code that shows up with something else.