intermittent check engine light

does it do this only when engine is hot? that is, after you've driven a few miles?

if yes, my guess would be fuel grade - ie. you're using premium gas instead of regular

Mine did that a couple of years ago and the error code was a sticky EGR valve. I used a can of Sea-Foam in my gas to clean it and the injectors, but any good fuel additive/cleaner will work. I throw a half can in every few weeks and has not ocurred again.

can you direct me to the location of the EGR valve ?

The EGR valve is on the manifold.. But you don't do anything to the valve itself. Just throw a 1/2 can of Sea-Foam in your gas tank when you fill up for the next few fillups and then once a month or so from then on. I also used a can of spray injector cleaner to spray directly into the intake manifold while you rev the engine up my hand. You would not believe all the crud that came out my tail pipe. My light has not come again....

Rick