I have a 95 Civic EX. My CEL has come on a few times in the last week, and I was able to use your advice to find the problem. Now it's just a matter of fixing it!
Thanks so much to all of you for the tips! DasSchmoo's links were very helpful. One thing I would add for anyone like me who is not much of a mechanic. The easiest way for me to get to the 2-pin connector is to get behind the glove box. To do that, I just emptied all the junk out of it, found the "stops" on the side that stop the glovebox when you open it. Spray those with some WD40 and wiggle/rotate them forward so the glovebox now opens about twice as much as it did. Behind it and on the far right are some connectors. I didn't see anything green, but it was the only blue connector with two wires going into it.

Now I just need to figure out how to fix my ECT sensor...