Brian,

You said it exactly right. Why not use whatever tools are at our disposal to keep our cars running right and to minimize lost time?

I have a 2001 Japanese SUV that had the CEL come on at 30K. I took it to Autozone, which provides free code reading for cars with OBD II. Its codes were for the O2 sensors. In this case there were four, and the code reader didn't say which was bad. I decided to take the car home and inspect all the connections before I purchased a new O2 sensor. As I was leaving the parking lot at Autozone, my battery went flat. They checked the battery and it was toast. I bought a new one right there. The guy cleared my codes, and no CEL ever since.

My point is that I don't have total faith in the code system.