One of the most common reasons for the check engine light to come on is a loose gas cap and it is the first thing you should check if that light comes on. A simple fix, it certainly doesn't require expensive auto repair, and you can go back to driving with peace of mind. So why would such an innocuous thing cause a warning light to come on in the first place? Well, the sensor is actually measuring pressure in the gas tank against a systemic average, looking for digressions that could be a sign of something serious. Sometimes it is something serious, but often times it is just that pesky gas cap.
Don't overlook sensor malfunction as a possible cause. You can't go three days without hearing an old timer lament the fact that today's computer-driven cars can't be worked on like the cars of yesterday. While for the most part this is just a resistance to change, there is some truth to the fact that increasing technology also means increasing sources of problems. Auto repair specialists will quickly check to make sure it isn't the light itself that is malfunctioning, rather than something serious. Many people have also found that getting water into the engine area can cause these sensors to act up.
Bad spark plugs are the final, simple solution to the check engine dilemma. If they are worn, cracked, or misaligned, it can cause a misfired spark, which in turn can cause the light to come on. After you've checked the gas cap, you might want to check the spark plugs. If they look worn and tired, it could be time for a change. You can do this inexpensively on your own and avoid costly auto repair.