stretchjob

I read some old threads on this earlier, and at lunch took it to Advance Auto where they plugged in their diagnostic unit. However my car didn't respond, even with the engine running.

He unplugged and replugged the thing in a couple times but still the same.

He said to drive it around some more and come back later, that the code might show itself after some more time.

Any truth to this? Thoughts/experience appreciated.