What Does the Check Engine Light Mean If It Turns On?

up-close look at a blue car

The check engine light is commonly known as malfunction indicating light. Your check engine light coming on is an indicator that something is wrong. Depending on the seriousness of the problem you are dealing with, your check engine light may blink or remain stable.

Why Does the Check Engine Light Come On?

A flashing check engine points to a serious issue. If your check engine light blinks while you’re driving, pull over to the side of the road immediately, or your car may sustain serious damage. At this point, consider having your car towed to your mechanic’s workshop. A steady light indicates a minor problem, and you can continue to drive, but take your car to an auto repair shop for a thorough inspection or the best auto repair in Sonoma County as soon as possible.

Here are some common problems that can cause the check engine light to come on

Loose Fuel cap

The fuel cap is an important part of your car’s fuel delivery system. It is designed to prevent gasoline vapors from escaping the fuel tank. If your check engine light comes on immediately after you refuel your car or pull over, make sure the fuel cap isn’t loose. Check your fuel cap to see if it is damaged.

Catalytic Converter Malfunction

A car’s catalytic converter converts the carbon monoxide produced during the combustion process into carbon dioxide. A malfunctioning catalytic converter can affect your car’s fuel efficiency and also cause your engine to stall. Regular car maintenance will keep your catalytic converter in working order. If you drive short distances, take your car on the highway from time to time to prevent the catalytic converter from clogging.

Mass Airflow Sensor Fault

A car’s mass airflow sensor measures the amount of air entering the engine so the ECU can determine the ideal air-to-fuel ratio. Some common signs of MAF malfunction include starting trouble, rough idle, and a sudden change in the throttle pedal position. The problem is usually caused by an old or clogged air filter.

Spark Plug/Ignition Coil Problems

Your car’s ignition coil produces the electricity the spark plugs need to ignite the fuel and air mixture. Diesel cars do not have spark plugs and ignition coils. Worn, mishandled, and improperly installed spark plugs can cause engine misfires and acceleration problems. Faulty ignition coils can cause your car to shut off unexpectedly while you’re driving.

Vacuum Leak

The vacuum system of a car is responsible for reducing vehicle emissions by routing the fumes as gasoline evaporates through the engine. In many cars, the vacuum system also helps the brake booster in improving braking performance. Some common causes of vacuum leaks include dry vacuum hoses, damaged fittings, and loose connections.


GreenTech Automotive is a leading auto repair shop in Sonoma County. Our technicians have years of experience servicing and repairing different types of cars. To schedule the best auto repair in Sonoma County, call (707) 545-7076.