Just have autozone check for codes periodically, or purchase alex pepper's software and cable
www.obd-2.com very worth it, might help you track a problem down as well. As far as resale value, just when u go to sell it, reset the computer and it should stay off for a while,, if it's coming back quickly, then I'd think it's a pretty bad problem and shouldn't be that hard to find. And if one shop can't find the problem,,,,, maybe another could.
