[LWJ]

So here is something I understand but am confused at the same time.


OBD2 scanners. I have a cheap-o from who knows where. I does read codes. Except when it doesn't. Sometimes you need to go to a legit mechanic to get the codes read because my poor scanner doesn't pick them up.

In my very simple brain I think that a digital signal is a signal is a signal. And a reader should be able to extract it.

Can anyone explain how a cheap reader can in fact read codes but at the same time not pick up other codes?

Thanks all!