What is On Board Diagnostic?
 

I seem to notice, there is a lot of reference to OBD I and OBD II in this forum and the camaro forum when answering a lot motor and ecu questions. But being a noob, I never really know what it means. There really isn't any information in site that really explain it.

What is the difference between OBD0, OBD1, OBD2?

This website also helps though
click me

RE: What is On Board Diagnostic?
 

Its a diagnostic program that the car runs. The ecuusessensors to monitor for problems and if it finds one it will throw a check engine light. So now the mechanic or you can go in and ask the ecu where the problem is. I think that OBD2/OBD2A/B are just more advanced diagnostic programs.

Anyway, I think thats what it is all about, I may be a bit off.