Follow-Up:
I have a 1999 and my check engine light came on at 10,000 mi. I continued to drive it and it went out at 15,000. It stayed out until 20,000 when it came back on. It has now gone off at 30,000 mi. It has 33,000 on it and the light is still off. I have noticed no difference in performance whether it is on or off. It appears to me to be built-in service expenses. I am going to keep driving mine and see what happens.