Be -very- careful with Craigslist. Massive amounts of scams going on. Take an inspection cert with you to the buy so you can compare it against the cert they show you. It's really common to photoshop a passing grade, reset the computer by pulling the battery and saying 'See? It passed emissions.' Then on the drive home, the check engine light comes on and you find out you've just been screwed.
Yeah, the engine light "trick" is an easy scam. You can buy a cheap ($80) OBDCOM and reset the light on any vehicle with a laptop. Don't have to get dirty and sweaty pullin' the battery. You can also get an idea of why the light is on with basic codes. When the buyer takes if for emissions the light is out but the problem hasn't been fixed. The quality computers can't get a read. Then, you have to go through a "drive cycle" to reset your onboard. To reset my Saturn, there's a routine I have to follow:
Idle 2.5 minutes AC and rear defrost on
Accel to 55 MPH ½ throttle
3 minutes at steady 55
Decel to 20 MPH (no breaks)
Accel to 60 MPH ¾ throttle
5 minutes steady at 60 MPH
Decel no brake to end of cycle
To do the drive cycle, I have to hit 28 in VA around 11 PM. That way, I can do it and not get caught in traffic.
Once you do all that, your onboard resets, gives the inspector an error, the engine light may come back on and it fails inspection anyway.
BTW Each vehicle has it's own "drive cycle" and a trained inspector can tell you what that is for your vehicle.
