I have a 2000 honda civic with 93000 miles. It came up with a p1456 code last week, still runs fine. I replaced the gas cap, but the light is still on. Does the civic need to have the check engine code re-set somehow, or do I still have a problem? The code came on last week after driving about 10 minutes. Now it comes on as soon as I start the car.
Try doing this, while holding the trip counter button, turn the ignition on off on off and then start the engine. Keep holding the button until all the dings and chimes and the engine service light goes off. This may not work on your year car but if it does and then the engine light comes back on after a while, you'll know its something else. If it does not come on then don't worry if the car is running fine. Honda programs the computer to turn the light on from five to seven thousand miles so they can get your money just to scan it and turn it off. Man I hope this helped. Vandragon