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Why Is My Check Engine Light On? Here Are the 5 Most Common Meanings

CarShield Team

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Tips & Advice

As a general safety feature, all cars or light trucks include an onboard diagnostic (OBD) system. When this system senses mechanical failure, it often illuminates the “check engine” light to notify the driver that the vehicle needs attention. But, when this does happen, the dashboard isn’t able to tell you what caused the malfunction—just that you need to look into it. So why is your check engine light on? We’ll walk you through what that looks like as well as the five most common causes for why the check engine light may be on.

What Does the Check Engine Light Look Like?

The check engine light will be on your dashboard (or "instrument cluster") behind your steering wheel when you sit in the driver’s seat of your car. It may look like a small engine or may say “CHECK ENGINE” or “SERVICE ENGINE SOON.” The color of the light may be yellow, orange, amber, or red. This same light could be solid or flashing depending on the severity of your engine issue.

What to Do When Check Engine Light Comes On

Sometimes you might not even need to look at the check engine light to know something is wrong with your car. You could be able to tell something is up based on some pretty clear conditions, such as your engine not turning on. However, when problems are not as obvious, your check engine light will be the first indicator that you’ve got a problem.

Before we talk about some possible causes for why your check engine light is on, there are a few things to consider in order to determine your next steps.

Is the Check Engine Light Flashing or Solid?

When you notice this check engine light turn on, take notice of whether or not the light is solidly on or if it is flashing on and off. If you see a solid check engine light, then that’s your OBD system telling you that there’s an engine issue but it’s not going to cause immediate damage. You can therefore continue to drive (carefully) and then start looking for a mechanic’s help once you get to your next stop.

However, if you see your check engine light flashing, you should calmly pull over at the next safest location to see what’s going on.

If you’re in that scenario, it will be helpful to call any roadside assistance you have on hand. If you have a plan through CarShield, for example, your coverage automatically includes 24/7 roadside assistance and towing, as well as rental car options. So, until your check engine light turns off or resets, CarShield administrators will be there for you to help you through the process of fixing your covered repair.

How Does the Drive Feel?

Once you see that check engine light on, take a quick assessment of how it feels to drive your vehicle. Is the car driving normally, or did your speed suddenly drop? Or did you start hearing a concerning rumble from the engine? Take note of any significant changes to your driving experience.

If your check engine light is solidly on and your driving experience still feels normal, you can keep driving cautiously and look into a repair at your next convenience. However, if the check engine light is flashing and your driving experience is suddenly changed, then you should pull over as soon and as safely as you can. Then start looking into repair help.

As a side note, your check engine light may illuminate when your car simultaneously activates a “limp mode.” When that happens, your car will cap your speed and turn off power for any unnecessary accessories so that your car at least has a chance to hobble home in its “injured” state. Some cars are built with this mode included to minimize further vehicle damage. That also counts as a safety feature! It won’t be helpful if your car experiences mechanical issues while you’re cruising at 70 mph with no clue that your car is starting to fail.

What Does the Check Engine Light Mean?

Unfortunately, as we mentioned before, the check engine light can only tell you that there is a problem—it cannot tell you what that problem is. There are, however, a few common causes for the check engine light to be on. Below, you’ll find the five most common reasons for check engine light-related car repairs as of 2023, according to CarMD.

  Possible Problem What Does This Issue Really Mean?
1 Malfunctioning (or Missing) Catalytic Converter A catalytic converter protects the environment by converting carbon monoxide from your engine into carbon dioxide. Without this car part, your car probably can’t pass emissions tests. Catalytic converter malfunction may be a contained issue or it may have been caused by the failure of a related car part.
2 Broken Oxygen Sensor Your car needs a specific amount of oxygen and fuel to function efficiently. Oxygen sensors in your vehicle measure how much O2 is left in the exhaust gasses exiting your engine. If this sensor picks up on too much or too little oxygen in the exhaust gas, it will send signals to another part of the engine to adjust how much fuel is being allowed into the engine cylinders.
3 Ignition Coil or Spark Plug Problems Your car needs continuous controlled “explosions” to generate the necessary power to move. The ignition coil takes low-voltage electricity from your battery and converts it to high-voltage energy. That converted energy is delivered to the spark plugs so they can ignite the fuel needed for engine combustion. When either of these parts stop working, your car can’t start.
4 Mass Airflow Sensor Issues Your mass airflow sensor (MAS) determines the correct air-fuel mixture needed to run the engine by measuring how much air is entering the engine. If this part fails or gets too dirty, it may not be able to identify the appropriate amount of required gas.
5 Loose or Faulty Gas Cap That little screw-on cap for your gas tank may be more important than you think. Aside from keeping gas in your tank, it also prevents gas from evaporating and helps your fuel system circulate properly. Due to its importance, if your car senses a problem with that gas cap, it may turn the check engine light on.

What Happens if I Ignore My Check Engine Light?

If your car still seems to run ok while showing a check engine alert, do still remember to investigate the cause for the check engine light. Ignoring it could seriously damage your car or cause your car to use up more fuel than it needs to. Even if you’re still able to drive your car, it’s possible that your vehicle is only getting more and more damaged as you drive it.

Additionally, if you don’t take care of a known issue with your car, certain conditions of an insurance policy or vehicle service contract may be voided. That means that, if you don’t address car issues in a reasonable manner, your protection plan may not cover certain repairs for your car.

Finally, if your check engine light is on, your car may not pass a car inspection or emissions test when you are required to have one. That can create an additional headache for you at a time when you would have preferred to avoid extra repair charges.

How to Turn Off Check Engine Light

Before you try to turn off your check engine light, make sure you do everything you can to find out the cause of the issue. It is not advisable to try to turn it off without fixing the problem first. Doing so could cause additional damage to your car or, worse, could eventually endanger you and people driving around you.

When the issue is resolved and you’re ready to turn off the check engine light, then you should consult your owner’s manual or your local mechanic for the steps to reset your check engine light. Steps to turn off a check engine light may be different depending which year, make, and model your car is.

Check Engine Light On? Plans Through CarShield May Help.

No matter when your check engine light surprises you, you’ll be glad that you have a vehicle service plan through CarShield. After using the complimentary 24/7 roadside assistance, towing, and rental car options while your car is in the shop, our administrators will be able to help you with the bill for your covered repair. Not only that, but CarShield members can enjoy a variety of other benefits with their vehicle protection coverage! Call the number or click the “GET FREE QUOTE” button at the top of this page to get started!

  Published By  
Sarah Solomon
Senior Editor & Copywriter at CarShield

Sarah is the senior editor and copywriter at CarShield. Her relationship with cars began when she started racing in the local Soap Box Derby as a kid. Now, Sarah gets to drive more complex vehicles—which is great even though she doesn't earn trophies for driving anymore. She writes out of St. Louis, MO.

Since having CarShield, Bill has had 2 claims on his Ford F250 to save over $2,000 in repairs.
Since having CarShield, Bill has had 2 claims on his Ford F250 to save over $2,000 in repairs.

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