"Check Engine Light" Mystery, It appears only to suddenly disappear... Options

[TheRockman]

OK, here's the deal. This past Sunday while driving home I get the infamous "Check Engine Light". My odometer had just rolled over to 139,149 miles. I mean just clicked into that mileage and the light turns on. SURPRISE!

So I'm thinking, "Oh crap here it goes. Here's where the engine becomes a cranky old man." But this morning, I'm driving to work and the light turns off! Nothing! Again, the odometer had just clicked over to 139,234 when this happend.

So good news: Check engine light is gone. Mystery: Why did it come on in the first place?

I know that my Dad's old Dodge Caravan would turn on the check engine light at about every 50,000 miles (which was crap) and that was the first thing that came to mind about this situation.

I'm going to get the car checked out Friday and see if any codes were stored or if it's still throwing some sort of trouble code without the light.

In the mean time, does anyone have any ideas about what might be going on? Has this happened to anyone?

[TheRockman]

Alrighty, here's the verdict.

Reading the OBDII port resulted in the code PO446 which is an "Evaporative emission control system vent control circuit malfunction." My mechanic said that a few possible causes could have been a loose gas cap, loose hose, or a bad charcoal canister. Since it could have just been a fluke, he cleared the code. If it comes back we may need to investigate further, but for now it's off and I'm happy.

Anyone have suggestions on things I should check?