The check engine light may well be the most misunderstood light on your dash, and can be caused by many different things. Most drivers aren't sure what to do when the light comes on, or what the light even means.
Your car's onboard diagnostic system (OBD) is constantly monitoring your vehicle to make sure the electronically controlled systems in your vehicle are working properly. By doing so, your car is making sure that you engine is producing peak power, getting the proper fuel economy, and not polluting the environment.
When your check engine or service engine light comes on, it may be something as simple as a faulty gas cap. It may also indicate that there is a system that has failed and needs attention. When the light comes on, it stores codes that can be read by your service facility that will point the technician in the right direction to start diagnosing the cause of the problem.
When the check engine light or service engine soon light comes on in your vehicle, Safford recommends that you first to check your gas cap and make sure that it’s on securely. If it was loose, properly tighten it and give the vehicle a drive cycle or two to reset the monitor. If the gas cap was already tight, all other gauges in the vehicle read normally, and your vehicle seems to be operating correctly, call your local service facility and make an appointment to have them run a diagnostic on your vehicle. In the rare cases that you have a blinking check engine light that is flashing red or that your vehicle is not performing properly, we suggest you take as much load off the engine as possible and find a safe place to pull over and call road side assistance.