"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?

[alltracman78]

When the ECU sees a problem, it turns the CEL on.
If the problem is not seen for 3 consecutive trips, it will turn the light off.
It WILL still store the code however.

This is most likely what happened.
You can go by Autocrap or somewhere and have them scan to see if it did store a code, and if so, what it is.
It would be good to know for future reference.

[TheRockman]

When the ECU sees a problem, it turns the CEL on.
If the problem is not seen for 3 consecutive trips, it will turn the light off.
It WILL still store the code however.

This is most likely what happened.
You can go by Autocrap or somewhere and have them scan to see if it did store a code, and if so, what it is.
It would be good to know for future reference.

Sounds reasonable. I'm going to go tomorrow and have the car checked. I'll let you know what happens.