What Does the Check Engine Warning Light Mean?

Since the early 80’s, the check engine light can be found on pretty much every car made. The check engine light was implemented to try and keep engines running efficiently while reducing fuel consumption. As you drive along, the car’s computer monitors different aspects of the engine and exhaust to determine whether everything is working as intended. Anything abnormal and the computer will illuminate the light to alert the driver that a fault has been detected. Check out some of the car diagnostic tools via ProCarReviews OBD2 recommendations, to help you read the exact fault that has been detected.

While many dislike the check engine light and tend to ignore it, the check engine light can be a very helpful warning as long as you understand what it means.

What the check engine light means

As mentioned earlier, the main reason why the light was introduced in the first place was to try and keep engines as efficient as possible. When you first start the engine, the light should illuminate for a few seconds to verify that the bulb is working. You should replace the bulb if you don’t see it come on during startup. If the light stays on after startup, it indicates that the computer has noticed a fault somewhere and stored a code in memory to help identify the problem.

Some common reasons for the light to come on include faulty spark plugs, malfunctioning engine sensors, or even a loose gas cap. Check the gas cap first and ensure that it is fully tightened. If the gas cap doesn’t appear to be the issue, you’ll need to hook up a scan tool to the car and read the code to understand more of what’s going on. Usually the issue is fairly minor, but this warning light should never be ignored as small issues tend to develop into bigger, more costly ones, if neglected.

If you ever see this light flashing, that is an indication of a serious misfire occurring in the engine. You should pull over as quickly and safely as possible and shut the engine off. The misfire can allow unburned fuel to enter the exhaust system and then reach the catalytic converter. The catalytic converter operates normally at several hundred degrees so the fuel ends up burning inside the exhaust which raises the temperature even more. Too much heat and the catalytic converter will be toast in no time and you’ll have an expensive repair bill on your hands. You should have the vehicle towed in this situation to prevent any serious damage from occurring.

Is it safe to drive with the check engine light on?

Even if this light is on, it doesn’t mean that the fault is currently happening. Certain faults may only happen every now and then, but the light will remain illuminated until certain parameters have been met. Usually, this involves driving the car normally and if no fault has been detected for a while, the computer will turn off the light automatically. It’s always best to have the light checked out, but sometimes driving normally for a few days can shut the light off and you won’t see it again.

If you are able to notice a difference in how the car drives, then it is likely the light won’t turn off until the issue has been resolved and you should not ignore this warning in this situation. As mentioned, if the light is flashing, significant damage is a real possibility and you should not drive the car until the issue is resolved.

If your check engine light is on and you’d like to know why, our certified technicians are always available to help you determine the cause of the problem.


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Dan

40 years of experience
1080 reviews
Dan
40 years of experience
Plymouth Grand Voyager V6-3.3L - Check Engine Light is on - Lawrenceville, Georgia
Mr. Dan Barber was quite patient, courteous and quite knowledgeable. From my observation, Mr. Barber appears to be quite professional.
Nissan Altima - Check Engine Light is on - Gainesville, Georgia
Dan is a super nice man that listens to your issue and does an easy to understand explanation so that you can truly take in, process and actually feel like you know what is going on with your vehicle and needed repairs. Honesty is what I felt I received. He wanted to make sure I was in a safe operating vehicle. His skill and knowledge level are exceptional. I will never use another car dealership for diagnostics or repairs. Thank You Dan!!!!!

Greg

23 years of experience
624 reviews
Greg
23 years of experience
Toyota Camry L4-2.4L - Check Engine Light is on - Phoenix, Arizona
Attention to detail and provided clear information to his findings. Acted in a Profesional manner throuout
BMW X5 - Check Engine Light is on - Chandler, Arizona
Greg was running a bit late due to business being busy but he comunicated with me very well, and let me know where he currently was and what time to expect him. Also he went above and beyond by showing me some small things that I could do myself to make my older BMW run excellent. Thanks Greg, appreciate your passion for your job

Keven

8 years of experience
187 reviews
Keven
8 years of experience
Subaru Impreza H4-2.5L - Check Engine Light is on - Spanaway, Washington
Very professional courteous respectful knowledgeable explains everything of the aspect of work and what needs to be done on the vehicle. Exceptional awesome amazing friendly and kind. 10+stars. I highly recomend friends and families if they need a experience mechanic is to ho to your mechanic and ask for Keven. Thanks again for an exceptional diagnostic repairs on my daughter vehicle. Very happy and pleased.
Hyundai Veloster - Check Engine Light is on - Tacoma, Washington
He is very informative, professional and friendly. He told us what was wrong with our vehicle in details, and gave us very helpful suggestions.

Brian

19 years of experience
138 reviews
Brian
19 years of experience
Nissan Juke L4-1.6L Turbo - Check Engine Light is on - Hampton, Georgia
Professional, knowledgeable, diagnosed problem very quickly. Provided me with feedback as to probable cause of the defect.
Chevrolet Trax - Check Engine Light is on - Covington, Georgia
Very professional/punctual & knowledgeable. I’d prefer Brian to repair my moms vehicle since I’ve established a rapport with him if at all possible when I’ve gotten my final quote that’s reasonable after choosing services/parts to perform the repair work.

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