I've an '07 Civic EX coupe. Auto. 70K+ miles. Never a minutes trouble till...

On Monday, wife was driving home from work. The gear indicator (green) light began to flash followed soon by the check engine light. Of course, as everyone else says, the indicator light quit flashing but the check engine stayed on. Took it to a shop yesterday where they read the code P0847. Local small time shop that ran from the repair. So, this am, I call another shop to schedule a repair (next Tuesday) and I'm driving it home just an hour ago and...magically...the check engine light has now gone off. No, the first shop didn't clear it...said they couldn't. And the 2nd shop hasn't seen it yet. So, I know Honda's are great cars. We like the Civic a lot. But really? Honda, heal thyself?

Suggestions on what may have the culprit and what to do next would be appreciated. You can leave off the go have a beer and be grateful cause I'm already doing that part.

Thanks for input!