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What to Do If Your “Check Engine” Light Comes On

The amber glow of the “check engine” light can make any driver uncomfortable. This is understandable considering the many reasons that could cause a “check engine” light to come on.

What Is The Check Engine Light

The “check engine” light is part of the vehicle’s onboard diagnostic system – the computer within the vehicle that monitors performance such as engine speed (RPMs), air to fuel ratio, and ignition timing. When an issue within the system is internally detected, such as engine misfires, deteriorating spark plugs, evaporative issues, or fuel mixtures running rich (less oxygen) or lean (more oxygen), the “check engine” light or “service engine soon” light will illuminate.

What happens if you continue to drive with your engine light illuminated? You may not notice that your vehicle’s performance begins to weaken right away. However, your fuel mileage may not be running as efficiently as possible and could be emitting high levels of pollutants into the air.

Here’s what you should do if your “check engine” light comes on:


Check the gauges on your dashboard. Do they indicate that your vehicle is experiencing low oil pressure or overheating? These indicators mean you should pull your vehicle over and shut off the engine immediately.

Check Your Gas Cap

Try tightening or replacing your gas cap. Gas caps these days have special seals as part of the vacuum fuel system. Sometimes a broken or misplaced rubber seal (on the gas cap) can trigger the “check engine” light to come on.

Reduce Pressure

If you notice that your vehicle’s performance has decreased, reduce your speed and avoid towing or transporting heavy cargo.

Avoid Emissions Testing

If your check engine light is on, it’s highly likely your vehicle will fail your state’s vehicle emissions test. In some states, your vehicle will receive an instant failure—even for a loose gas cap. Be sure to make sure all issues are resolved prior to your test.

When Your Check Engine Light Comes On

If the “check engine” or “service engine soon” symbol illuminates, observe whether the light is constant or flashing. A solid glow indicates your vehicle should be inspected soon, as there are many different causes (some vehicles have 200 codes, alone!). A blinking “check engine” light, however, is cause for concern and indicates that your vehicle needs immediate attention. It is highly recommended that you bring your vehicle in for further inspection by a trained professional. Waiting too long could cause further damage to engine components, for example, damage to the catalytic converter or burning a valve within the engine, which could result in an overall loss of power.

If your “check engine” light or “service engine soon” light comes on, don’t wait! Stop into Sun Auto Service today. Our highly trained, professional technicians will perform the proper diagnostics to determine the cause of your engine issues and get you back on the road, quickly.