Honda CRV 2003-check engine light?

My check engine light won't go off; it has only 40,000 miles on it (real mileage). I also bought a new gas cap--so that isn't it. Can't find my manual either. How do I reset it, I'm thinking it is for oil maintenance but that was changed 1500 miles ago. I'm trying to avoid a trip to the dealer. It runs great and the gauges don't indicate any problems--Thank you for any help you can give me.

If fitting the new gas cap doesn't cause the Check Engine light to go dark within a few days, call an independent Honda repair guy to read the code for you. There may be something else like a bad Oxygen sensor or weak spark that's not too expensive to fix. Don't ignore the Check Engine light for more than a few days, because you might damage something more expensive (like the catalytic converter) if you drive on a long trip with the light glowing; or you might be wasting fuel with a thermostat stuck open and the engine running too cold, for example.

Please listen closely. Take the car back to a Honda dealer because the emissions system has an 80,000 mile or five year warranty!

The Honda Dealer are the only people who can test your fault code and then will know the *exact part that needs to be cleaned or replaced.