Please, I have a honda civic 2006 model that has that check engine symbol on. What does it mean?

Can usually come on for many different reasons. A dealer, many auto shops and even some well-known parts stores can access the necessary data from the car's onboard system and most likely tell you where the problem lies. Could be a relatively minor adjustment or component replacement needed with emissions system-depending how your warning system is designed.

Attach a code reader to the Data Link Connector, located under the dash, turn the ignition switch to ON, and read codes. They could range from the gas cap being loose to something more serious.

Now that you mention it greasemonkey, the only time I ever had a check engine light come on was just after I refueled and removing and reinstalling the gas cap turned it off. Good suggestion.