Chceck Engine light and ROOM fuse

Hey.  I have a 2000 Protege ES and my check engine light recently came on.  I checked all the fuses and they were fine and then when I turned on the car the check engine light was off.  Now about 30 miles later it is back on.  Thoughts?  Also, is there a specifc fuse called ROOM fuse. If so, where is it?  I can't find it - manual talks about it but doesn't give location.  I checked fuses under the sterring wheel and under front hood.  Thanks.