DOT into your OBD

[kozakvod]

One of the things I had read from someone on another forum was that they were "checking" for fault codes. I guess (I know it's not that way on my truck) but I gathered the CEL could be shut down and by 'plugging in' they could see if a fault existed in the ecm. Now I don't know whether or not they could read what the fault was or not, but I know in our 4 wheel cars around here you can't have a CEL on or active fault to get a annual inspect.

But as I was reading about these it got me to thinking, WHAT exactly could they see? And I do agree with @SquareOne in that plugging into my ecm would not fly and I would need to see some serious regs that gives them the authority to do that, for the sake of it.