What Does the Check Engine Light Mean?

The dreaded engine warning/service engine light. We fear it because we do not understand it.

It is part of your vehicle's diagnostic system. Basically, it's a way that your vehicle communicates to you that it needs attention. What kind of attention? When your engine warning light is illuminated, it could mean a number of different things.

Fuel Delivery System

One thing you want to immediately check is your gas cap. Your fuel system is pressurized. A loose gas cap can create a signal that pressure is low. It could also indicate a number of issues in this system. For instance, your oxygen sensor may have gone bad.

Spark Plugs

Bad spark plugs diminish engine performance. You could experience reduced power if they are not sparking properly. Your engine warning light could indicate a need to replace spark plugs.

Mass Airflow Sensor

Just as you'd think, this sensor measures the flow of air into your engine. This in turns tells your engine how much fuel is needed. A faulty mass airflow sensor can illuminate your engine warning light.

Do NOT confuse the "engine warning" light with the "service required" light.

The latter indicates a routine maintenance is due. The engine warning light indicates a possible issue and if it still on after you have checked the gas cap, you should definitely have your vehicle serviced.