Computer Diagnostics
When this light comes on AUTO LAB can plug in your computer data link, retrieve codes and diagnose them. At this point we can advise you of the severity of the problem, give you our professional advice and a estimate for cost of repairs.
The "check engine" light is part of your car's onboard diagnostics (OBD) system. Since the 1980s, computers control and monitor vehicle performance, regulating such variables as engine speed (RPM), fuel mixture, and ignition timing. In some vehicles, the computer also tells the automatic transmission when to shift.

When the computer finds a problem in the electronic-control system that it can't correct, the computer turns on a yellow warning indicator that's labeled "check engine," or "service engine soon.” This light could also be a picture of an engine, known as the International Check Engine Symbol, perhaps with the word "Check." In addition to turning on the light, the computer stores a "trouble code" in its memory that identifies the source of the problem, such as a malfunctioning sensor or a misfiring engine. The code can be read with an electronic scan tool or a diagnostic computer, standard equipment in auto repair shops.

If the "check engine" light illuminates, it will either blink or remain constant, depending on the problem. Either way, you should have the vehicle checked by a service technician. Your “check engine” light indicates a problem that needs immediate attention. In late-model cars, a blinking light usually indicates an engine misfire so severe that unburned fuel is being dumped into the exhaust system, where it can quickly damage the catalytic converter, requiring an expensive repair if not corrected. If that happens, you should reduce power and have the car or truck looked at as soon as possible. If the light is steady, the problem is not an emergency, but you should schedule an appointment as soon as possible. Today's automotive computers often try to compensate when there's a problem; so you may not notice deterioration in performance, even though your fuel mileage is suffering and your vehicle is emitting unacceptable levels of hydrocarbons and other pollutants.
Check your dashboard gauges and lights for indications of low oil pressure or overheating. These conditions mean you should pull over and shut off the engine as soon as you can find a safe place to do so. On most cars, a yellow "check engine" means investigate the problem giving you time to schedule an appointment to have your vehicle diagnosed.

    Try tightening your gas cap. This often solves the problem. Keep in mind that it may take several trips before the light resets.
    
    Reduce speed and load. If the "check engine" light is blinking or you notice any serious performance problems, such as a loss of power, reduce your speed and try to reduce the load on the engine.
   
     In most cases, you’re probably better off taking the vehicle to a professional instead of trying to diagnose the problem yourself. Make an appointment with a service center to have the code read and the problem fixed.
    
    Don't go for a state emissions test. In a latemodel car, an illuminated "check engine" light probably is a sure sign your car will fail the test. By the way, don't bother trying to fool the inspection station by disconnecting the battery or using any other method to erase the trouble code and turn off the "check engine" light. Your vehicle's computer will let the inspection station know that its codes have been erased, and you'll just have to go back again.
.
Tips if Your Check Engine Light Comes On