Warning lights are meant to alert you that there is an issue with your vehicle and that something needs to be attended to. When a warning light comes on in your car, it can be stressful not knowing what it means. This is especially true with the check engine light, which can be connected to all kinds of problems. 

If you are dealing with a check engine light in your car, you will probably want to get to the bottom of it quickly. It could be a serious problem or it could be as simple as a change in humidity. Understanding some of the most common problems associated with this light can help you feel more confident when it turns on. 

### Can You Drive With the Check Engine Light On? 

For the most part, you can drive safely with your check engine light on. However, depending on what the light is warning you of, continuing to drive could make the problem worse. At the very least, it is best to have your car's computer read and see what kind of trouble code it is receiving so you can know if the issue is pressing. 

In states that require you to pass a smog test, a check engine light will immediately disqualify you. Even if you turn the light off manually, the tests can determine that there is an issue with the engine or emissions and you will not pass. If you have an emissions test coming up and your check engine light is on, you will need to get the issue that is turning on the light fixed before you bring it in.

### What Does the Check Engine Light Mean? 

There are many different reasons that a check engine light will turn on. However, the way it is displayed will also matter. It can usually give you a good idea of whether or not your car is safe to drive in its current state. 

__Solid Light:__
Most of the time, your check engine warning light will be solid when it turns on. This means that there is a problem somewhere in the engine and that it could be any number of things that range in severity. Sometimes, even a slight change in the weather can trigger the light. Usually, a solid check engine light doesn’t mean that it is unsafe to drive unless you are noticing a significant change in the vehicle's performance. 

__Flashing Light:__
If your check engine light is flashing, this could mean that there is a more pressing problem and your car needs immediate attention. Emergencies such as a misfire could potentially cause a fire and will trigger a flashing check engine light. If you are driving and notice the warning light flashing, it is best to pull over as soon as possible and get your vehicle towed to a car repair shop. Driving with the light flashing can cause significant damage and even engine failure. 

### What to Do if Your Check Engine Light Comes On 

If your check engine light comes on, there are a couple of things you can do to try and resolve the issue. Depending on the reason for the indication, you might even be able to turn the light off. However, if the reason is related to something that needs attention, it will always turn back on. 

__Disconnect and Reconnect the Battery:__
If you want to know if your check engine light is related to engine problems that need to be fixed, you can try turning it off. By disconnecting and reconnecting the battery, you can reset your vehicle’s CPU, which will turn off the light. If the light was for something like a change in humidity or a temporary issue that has resolved itself, it will not turn back on. Most of the time, though, it will come on again once you have driven enough for the CPU to run all of its checks. 

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__Purchase an OBD-II Reader:__ 
All vehicles that have a computer will have an OBD-II reader port. This stands for On-Board Diagnostics System and a scan tool can be plugged into the port where it will receive a diagnostic trouble code from the computer. With that code, you can go to OBD-Codes.com and take a look at what the check engine light is related to. Oftentimes, this code will not tell you specifically what is wrong but instead what area of the vehicle is having the issue. 

If you don’t want to purchase your own code reader, there are other ways to get the code read. Many automotive part stores will offer free code reading as a service and can check your CPU for you. They will also be able to tell you what the code means and what your next course of action should be. 

__Take Your Vehicle to a Shop:__ 
Your best bet with a check engine light is to take your vehicle to an auto repair professional. They will have more sophisticated diagnostic equipment than you can buy or what an auto parts store will have on hand. With this equipment, they can do a diagnostic test and diagnose the exact problem. Then, they will let you know how severe it is or whether your vehicle is safe to continue driving. 

### Common Causes of a Check Engine Light 

One of the issues with a check engine light is that it can be fairly ambiguous. All it means is that the computer has detected an issue and you will need to address it. However, there are some common reasons the check engine light comes on on that will be more prevalent than other reasons. 

__Oxygen (O2) Sensor:__
Your vehicle’s oxygen sensors are an important part of the exhaust system. They measure the amount of oxygen in the exhaust that has not been burned off in the combustion chamber. This allows the computer to regulate the air and fuel ratio and ensure that the car isn’t running too lean or rich. 

If you have an issue with an O2 sensor, this can set off the check engine light. Most O2 sensors will need to be replaced after about 80,000 miles. However, it is important to keep in mind that an O2 sensor code with a check engine light doesn’t necessarily mean the sensor itself has gone bad. It could also have something to do with how it is reading the oxygen levels or the levels themselves. 

__Loose Gas Cap:__
This may sound too easy but if your car has a loose gas cap, this could trigger the check engine light. In order for your engine to recirculate all the vapors from your gas tank, the whole system needs to be completely airtight and sealed. If the gas cap is loose, the vapors can escape and cause what is known as an EVAP emission control issue. Whenever you refill your gas tank, be sure to turn the cap until you hear a click to ensure that it is closed all the way. 

__Catalytic Converter Issue:__
If you live in a state where catalytic converters are required, you could get a check engine light warning if the one on your car is starting to fail. Catalytic converters convert carbon monoxide to carbon dioxide using a chemical reaction that breaks apart the exhaust gas. A bad catalytic converter is a common cause of check engine lights. However, catalytic converters usually do not fail on their own. There will be some kind of underlying cause related to the emission control system that needs to be addressed before you put in a new one. 

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__Mass Airflow Sensor:__ 
The mass airflow sensor works in conjunction with the O2 filters to determine the air-to-fuel mixture in the engine. They can become contaminated by things like oil, water vapor, and dirt and when this happens, the check engine light will turn on. Sometimes, the sensor will simply wear out and will need to be replaced. 

__Engine Misfire:__
The air-to-fuel ratio in your car’s engine needs to be just right for the spark plugs to be able to ignite properly. When there is an issue with this mixture, or the spark isn’t properly timed, this will cause what is known as an engine misfire. Misfires are potential emergencies and will usually be accompanied by a flashing check engine light. 

There are a lot of different reasons that your engine can misfire. Everything from a vacuum leak, bad spark plugs, or a broken fuel injector could cause your engine to misfire in one or more cylinders. If you are getting a misfire trouble code and you're noticing poor fuel economy, it is best to take your vehicle to an auto repair shop and have the problem diagnosed and repaired. 

__Ignition System:__ 
Your car’s ignition system includes many different systems like spark plugs, coils, and everything else that is needed to ignite the fuel in the engine. The CPU monitors all of these systems and if there is an issue, it will usually turn on the check engine light. You may also notice that the car takes longer to start or needs more tries to finally turn over. 

__Transmission Issue:__
The transmission is part of your vehicle’s overall powertrain and is connected to things like emissions and your vehicle’s combustion chamber. A problem with your transmission could result in all kinds of emissions and engine power problems, all of which will be picked up by the CPU and result in a check engine warning. 

### What is a Check Engine Light? 

The check engine light is also sometimes called the malfunction indicator lamp. It is connected to your vehicle’s diagnostic system and is generally an indicator that the computer has detected a problem. Most cars made after 1996 will have this light and it will be located somewhere on your dashboard display. 

Depending on your vehicle, the dashboard light will be orange, yellow, or amber and will have some variation of an engine icon. It may also say something to the effect of “Service Engine Soon.” No matter what the indicator looks like, it is trying to tell you that there is an issue with the way your engine is running.  

### Final Thoughts

A check engine light turning on can be a major source of anxiety for drivers. This is in part because it is so ambiguous and could be trying to warn you of both serious issues and minor ones. By understanding what some of the most common causes of the check engine light are and how you can find out what is going on, you can get your vehicle fixed quickly and get back on the road.

It's a problem that's likely happened to all of us: your car's 'Check Engine' light comes on and you have no idea what it means. Can you drive the car? Should you take it to the shop? Read on to find the answers to these questions and more. 

What Does My Check Engine Light Mean?

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