My check engine light is on: What should I do?

Quick insights

• The check engine light in your car has an important role to play in terms of keeping you safe on the road and maintaining your car’s functionality and value.
• A solid check engine light indicates less-urgent issues, while a flashing light signals an urgent issue that should be dealt with immediately.
• One of the most common reasons the check engine light comes on is a loose gas cap, which you may be able to fix yourself.

Depending on how familiar you are with car maintenance, seeing the check engine light on your car may have an ominous presence. In actuality, the check engine light is a very helpful indicator of how your engine is doing, alerting you of when it’s time to make repairs, often before things get worse. Depending on what has caused it to light up, responding to the check engine light quickly may help prevent more extensive (and expensive) repairs. In this article, we’ll explain what the check engine light means and what to do if your check engine light comes on.

Understanding the check engine light meaning

The check engine light is part of your vehicle’s onboard diagnostics system, which helps monitor your engine’s performance and emissions. The light, which is shaped like an engine (and on certain vehicles accompanied by the text “check engine”) will either light up in a solid hue or flash repeatedly. A solid check engine light typically indicates a more minor issue, while a flashing light warns of a severe issue that needs immediate attention.

Ignoring the check engine light (even when it’s only solid) can have a range of detrimental effects on your engine. The problem causing this light to appear could lead to increased fuel consumption, failed emissions tests or even major engine damage. Acting quickly may be necessary to maintain your vehicle’s value and performance.

Common reasons a check engine light will turn on

So, what are common reasons why the check engine light may turn on? Possible answers include:

• A loose gas cap: This minor but common issue can cause fuel vapors to release, decreasing overall efficiency.
• A faulty oxygen sensor: This important sensor detects how much oxygen is in your car’s exhaust gases. When it malfunctions, your car’s fuel efficiency may suffer, and emissions may increase.
• Worn or defective spark plugs: These small but important electrical components can lead to engine misfire or poor acceleration.
• Malfunction of the mass airflow sensor: This sensor measures the amount of air entering the engine and determines how much fuel is needed for efficient operations.
• Failing catalytic converter: When functioning correctly, this part of your engine converts toxic gases into less harmful substances before they are released into the atmosphere. When the catalytic converter fails, your car’s emissions are bound to increase.

Immediate actions: What to do if your check engine light comes on

If your check engine light is on, it’s important to remain calm as you perform a preliminary diagnostic on the issue. Pull over in a safe location to turn off your car and assess the situation. If you have your vehicle’s manual on board, you may want to consult it for model-specific guidance related to the check engine light.

Emergency situations

While most triggers for the check engine light will not be immediately dangerous, it’s important to know how to recognize a situation where you should stop driving and call for help. Start by looking for visible signs of engine distress, such as smoke or unusual noises.

• Smoke: If you see smoke, you should avoid driving and have your car towed for mechanical repair. Be careful about touching the hood of your car as it may be hot.
• Fire: If you see fire, move a safe distance away from your car and call emergency services.

Non-emergency situations

After checking to make sure there is no visible smoke or fire, you can look under the hood for common issues. With your car’s hood open, you should first examine the gas cap; as touched on above, a loose gas cap is a very common issue that can trigger the check engine light. In many cases, you may be able to tighten the gap to correct the problem. Acquiring an OBD-II scanner (an on-board diagnostics machine) can help you diagnose the issue yourself by reading your car’s error codes. Otherwise, you should plan to bring your car for professional diagnostics and repair as soon as possible.

How to reset the check engine light

Once the issue that caused your check engine light to turn on has been addressed, there are three ways for it to turn back off:

• Your mechanic may reset it: Your mechanic may reset the check engine light as part of the service before you pick up your car. Consider asking your mechanic about this detail before you leave the lot.
• Reset the light yourself: If you decide to reset the light yourself after repairs have been made, you will need to safely disconnect the car battery for about 15 minutes (ensuring all car electronics are off first).
• Keep driving: It may take a few driving cycles for the check engine light to turn back off again after repairs. If it fails to turn off, you may want to double-check that the original issue has been resolved, or that there is not a new or separate problem causing it to stay on.

In conclusion

When your check engine light is on, responding quickly can be very important for safety and maintenance. A formal diagnosis of why your check engine light is on, either from a mechanic or diagnostic machine, is a good way to begin the repair process. While seeing this light illuminate can be alarming, keep in mind the important role it plays in keeping you safe and your car in its best condition.