Your car’s check engine light comes on and off intermittently? Have you experienced frequent lighting up of your car’s check engine light without you switching it on? Are you worried about what might have caused such an issue with your car’s check engine?
Well, if all these queries have been running on your mind off late and you are looking for some reliable answers, then you are on the right page!
It almost seems like a nightmare for every vehicle owner when their car’s check engine light comes on and off while driving. Sometimes, you may also have weird feelings if it starts in the middle of driving during night hours and it can scare you to hell if you are traveling alone.
But if you know the reasons why your check engine light comes on and off intermittently, and what to do when check engine light comes on and then it goes off by itself, it will be easier for you to detect the problem quickly and solve it as soon as possible so that you do not get scared further.
In this guide, we will discuss in detail what does it mean when your engine light comes on and off, the reason behind it and how to deal with the same. So, keep reading the article thoroughly till the end and discover more information about your car’s check engine light here!
What Does Check Engine Light Mean?
If you have come to this page, you probably already know what does a check engine light mean, but we shall still brief you on more details about check engine lights and also discuss the difference between a flashing and solid check engine light.
So, what does check engine light indicate? An check engine light is basically a tool that indicates a problem with your car engine. Also known as MIL or Malfunction Indicator Light, the check engine was initially designed to monitor the car’s emission control system.
Now let us know the difference between a flashing and solid check engine light. As against the problem we are going to discuss in this article about the reason behind the check engine going on and off intermittently, one must know what the solid or flashing check engine means at first!
A flashing check engine light means there is an immediate emergency on your vehicle, and you need to stop right then to check for the reason, whereas a solid check engine light means you can check for the reason later, and there is no immediate emergency to be afraid of!
For the former case, you might even need the intervention of a car mechanic, while for the latter case, you can solve it without any immediate help! So, now that you know the car check engine light meaning, let’s jump to the next section to know the reason behind its intermittent on and off functioning!
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13 Reasons Why Your Check Engine Light Comes On and Off
Since now you know what does it mean when your engine light comes on and then it goes off by itself, it’s time to find out all the possible causes of this engine warning light situation. Here you will get to know all the possible and most common reasons why your check engine light keeps going on and off intermittently and what you can do to control such instances.
So without further ado, let’s check out each cause effectively and find out the exact reason why your car’s check engine is coming on and off frequently! Here we go:
Loose Gas Cap
This is one of the most common reasons why your car’s check engine light comes on and off intermittently. It can sound as vague as you can think, but a loose cap can actually cause your car’s check engine light to switch on. If you don’t tighten the gas cap immediately, it will continue to cause this problem till you get back to filling gas again and then tightening the cap properly.
Sometimes there might be a problem in the gas cap that prevents you from tightening it properly, and that is when the car check engine light on and off intermittently. If you notice this issue frequently, then you must not delay checking the gas cap and tighten it as soon as possible.
No wonder, even after tightening the gas cap, the check engine light might still turn on or turn off. And if the problem still persists, you should understand that the matter is something else, and the loosened gas cap is not what causes check engine light to come on and off. Then, check for the other reasons mentioned next to find out the exact cause.
Oxygen Sensor Malfunction
When the check engine light comes on and off while driving, it can also be due to a malfunctioned oxygen sensor. A loosening gas cap might be the most common cause behind the check engine light coming on and off intermittently, but if it is not so, then the next common cause can be a malfunctioned oxygen sensor.
The primary function of the oxygen sensor of your car is to keep track of whether your car’s engine is getting enough oxygen or not. When gasoline gets mixed with oxygen, the car engine runs smoothly. And if the amount of oxygen is less or too much, it can cause problems in the car engine leading to damages and problems in running the car.
Thus, the importance of the oxygen sensor is very high. And if you see check engine light came on then went off by itself, it generally indicates there is a problem in your car’s oxygen sensor, and therefore, it needs your intervention shortly to avoid any hazardous damages.
You must not delay in taking help from an expert and solve the issue immediately because a faulty oxygen sensor is dangerous.
Bad Spark Plugs or Plug Wires
Out of all the reasons why check engine light comes on and off intermittently, this one has the primary significance. In most cases, bad spark plugs or plug wires are the leading causes behind the check engine light coming on and off randomly.
Not only do bad spark plugs cause the check engine light to come on and off, but it also roots to various other issues. It includes declining acceleration of the car, the vehicle not starting up properly, the engine combustion being affected, etc.
And when you think of what is the most common reason for check engine light coming on and off intermittently, you can consider bad spark plugs without much hindrance. The worn-out spark plugs of the car engine affect the combustion process leading to several damages.
Initially, they might not cause major problems, but you can expect the issues to worsen with time. Thus, if you notice that the car check engine light comes on and off periodically, you should check the spark plugs and clean them up immediately.
If the condition is too bad, you must call an automobile expert to check the problem and take further action.
Faulty Mass Airflow Sensor
Are you still thinking, why does my check engine light come on and off? A faulty mass airflow sensor might be another reason this happens! When you drive your car, the air from outside enters your car engine through the air filter. The mass airflow sensor is responsible for measuring the amount of air getting inside the car engine through the air filter.
It is designed in a way that neither allows too much air inside nor allows less airflow inside the car engine. Thus, if it becomes faulty, it can lead to consumption of more fuel and cause other problems too!
If you notice the car check engine light came on then went off, you can conclude there is a problem with your car’s mass airflow sensor. And you should not ignore this problem too, even if it doesn’t cause significant harm to your car, you would not certainly like that your car eats up more fuel than usual.
With time, if the problem is not fixed, a faulty mass airflow sensor can damage several other parts like the spark plugs, the oxygen sensor, catalytic converter, etc. So, when the car check engine light comes on and off, root for a faulty mass airflow sensor!
Bad Ignition Coil
A bad ignition coil might be another reason for your vehicle’s check engine light to come on and off by itself while driving. The ignition coil is the part of the engine that helps in generating electricity that the engine spark plugs need to ignite the fuel and air mixture of the cylinders.
Most cars have only one coil, while some modern cars have more than one coil to serve the purpose. But it doesn’t matter whether you have eight coils or one; if there is a fault in them, you can notice that the car check engine light comes on and off intermittently. That is when you should take things seriously!
Because if the problem in the ignition coil is not fixed sooner, it can lead to more damage, and both the spark plug and the ignition coil can get damaged heavily! You can experience engine misfire and heavy calculation also if such things happen.
So, it is advised that if you want to find out what does it mean when your check engine light comes on and then it goes off by itself, then think of a malfunctioned ignition coil.
Bad Catalytic Converter
A bad catalytic converter might be one of the prominent reasons why the check engine light comes on and off intermittently during driving! For those who do not know, a catalytic converter is an integral part of the car’s exhaust system, and it works as a catalyst in the process of converting carbon monoxide into carbon dioxide during the process of combustion.
And if somehow it becomes non-functional or gets damaged, it can lead to serious havoc in your car’s engine and further functioning. So, when the car’s check engine light keeps coming on and going off, you can expect there is a problem in the car’s catalytic converter. And if you detect the issue, you need to fix it immediately, as the longer you delay, the more damaged it becomes.
In most cases, changing a damaged catalytic converter can cost you too much, and thus, preventing it from getting damaged is the best you can do to save a lot of money. You can do it by regular maintenance, taking your car out often, driving on the highway, etc.
So, if you are thinking, “why does my engine light come on and off” consider the bad catalytic converter a prominent reason.
Failing Aftermarket Alarm
If the aftermarket alarm on your car doesn’t get installed properly, it not only creates havoc with the car engine but can also cause the car check engine light to go on and off intermittently. The most common issues with a failing aftermarket alarm include:
- Preventing the vehicle from getting started.
- Draining the car’s battery.
- Stoping the car in the middle of nowhere.
- Several other such things.
So, if you find out that the car check engine light comes on and off randomly, then you can suspect there is a problem with the car’s aftermarket alarm. And if you are thinking; what is the solution to this problem?
The first and foremost thing that you must do when you find out about such a problem is that you should check the severity of the alarm installation. If you notice that you can fix it properly, then do it then and there.
But what to do when check engine light comes on? Well, in that case, there might be an emergency, and you might need to reinstall or repair the entire aftermarket alarm by a car mechanic, or else it can cause more havoc than you think.
It can cost you a bit, but the danger that is prevented by this immediate action is worth it anyway!
Exhaust Gas Recirculation Valve Failure
Are you still thinking about what does it mean when your engine light comes on and off intermittently? Well, a failure in the car’s exhaust gas recirculation valve might be another prominent reason behind such instances.
The EGR system or the exhaust gas recirculation system of the car engine is responsible for lowering the amount of nitrogen oxide coming out of the car engine. The hot exhaust gasses get directed to the combustion chambers through the EGR system, which helps in the easy burning of the fuel and hence reduces emissions!
But, when the car check engine light goes on and off frequently, it indicates there is a problem in the EGR; it can either fail entirely or get clogged partly.
Though the clog removal process is comparatively easier and can be carried out even if you have little mechanical knowledge about cars, you might need to replace it and get a new one if it is entirely at fault.
It can cost you a few hundred dollars for changing the OEM quality unit, but the result is all worth it! So, when you think of why does my check engine light come on and off, you know the reason!
Dead Car Battery
If you have been wondering what is the most common reason for check engine light to come on and off by itself, here is another reason you can check! We all know the consequences of a dead car battery, right?
It gives rise to several other issues than only just adhering to a non-starting car engine. If the car battery is not in a good condition or if it is completely dead, the replacement cost can be much higher. And you cannot really drive with a dead or almost dead battery condition.
So, whenever you notice that the car check engine light comes on and off intermittently, you can consider it to be a sign of a dead battery behind the other relevant reasons as well. So, what to do if you face a dead battery condition in your car?
You can take it to get charged first! It can run for a good few months if the car battery is properly charged and maintained thereafter.
But if you do not run proper maintenance or do not take out the car too frequently, you may need to replace the car battery entirely, which is a much more costly alternative. And if there is a dead battery, you get to know why does check engine light come on and off frequently!
Vacuum Leak
If the car check engine light comes on and off while driving, then it can also indicate a vacuum leak in your car! The vacuum system is part of every car operating system, and it helps in performing a lot of tasks. From operating the brake booster to lowering the car emissions, the vacuum system of the car performs a lot of tasks.
And so, if it doesn’t function properly, there is a risk in driving. The sooner you notice the car check engine light goes on and off randomly while driving, pull your car aside and check the vacuum system of the car. How to know there is a vacuum leak?
Well, if the car’s idle either settles or surges at a very high rpm, you can consider it to be the reason for the vacuum leak. The most common cause behind such vacuum leaks could be extreme temperature conditions, loose connection, cracked fittings, etc. While repairing it doesn’t cost too much, finding the exact point of the leak might be a difficult task!
Engine Misfires
Another important cause why check engine light comes on and off while driving can be engine misfires! The primary cause behind engine misfires is the engine cylinder not producing enough power to spark the car engine. When you are accelerating or when the engine is under too much load, then also such misfires can occur!
No wonder you do not want such misfires to occur too frequently, as the misfires can lead to certain types of jerks that you would not like to experience very often! And, it is recommended that you root for the power cylinders of the car engine when the car check engine light on and off intermittently.
The immediate intervention of a car mechanic or an automobile expert might solve the problem quickly and without much expense. You should not overlook such engine misfire conditions if you find such instances while driving.
It is because such engine misfires may not look too dangerous immediately, but if it is overlooked for a longer period, it may lead to havoc and damages that you do not wish to experience with your car!
Overheating
Are you still wondering what does it mean if your check engine light comes on and off? Another common reason behind such intermittent check light flashes could be the car engine getting overheated rapidly.
It occurs mostly during hot and humid temperatures when the car engine system gets hot effectively, and any coolant doesn’t work properly to control the heat. It is then that you can experience overheating, which eventually leads to the car check engine giving signals of a malfunctioning system unit!
Though it is not too serious to intervene immediately when you experience the car getting overheated, if you do not take quick action to lower the heat or control it from being overheated for a longer time, it can cause more trouble to your car than you can imagine!
So, what to do when check engine light comes on and off intermittently after getting overheated? It is as simple as pulling or parking your car in a shaded area, getting some coolant for the car engine, and also keeping the car hood open for some time, and letting the car cool down eventually before you start driving again!
Diagnostics Malfunction
Are you still wondering why does the check engine light come on and off randomly while you drive your car? Well, consider this last cause to be another primary and significant problem behind such issues!
All the reasons mentioned above can be the cause behind the car checking engine flashing lights intermittently to signal about a problem in your car. But sometimes, what happens is that even if you think you have diagnosed the exact cause behind such malfunctioning, your diagnosis can go straightaway wrong without you even knowing about it!
So, you might think; why does my check engine light come on and off, even if you have checked for the possible reason and you are sure you fixed it well. That is when the diagnostics malfunction works for you!
No matter how expert you are in detecting an issue when checking your car, you may still leave a loose point, and the problem can be different than what you concluded. Thus, it is recommended that even if you have diagnosed the problem with your car, you get it checked by an expert if the check engine light on and off intermittently while driving and refuses to stop!
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Is It Safe to Drive with Check Engine Light On?
As the check engine light signifies the car engine’s onboard diagnostic system, it is only normal to think whether is it safe to drive with check engine light on!
It certainly is not safe to drive while your car’s engine light comes on as it indicates an emergency, but you have to see the nature of the light. As mentioned above, when the light is flashing, it indicates danger, whereas if the light is solid, then you can still drive the car without immediate intervention.
So, what to do when check engine light comes on? At first, you need to park your car in a safe place and then start by checking the immediate causes that you know of!
If you cannot diagnose the problem by yourself, you should call an expert immediately. If the check engine light keeps coming on and going off, you already know the reasons, and you can diagnose the problem easily!
Why Does My Check Engine Light Come On and Off?
Till now, you have read about all the prominent reasons why check engine light comes on and off while driving and other relevant information regarding the same. Sometimes it might be the fault of the vehicle’s spark plugs, while sometimes, it may be due to a dead car battery.
But no matter what the reasons, you must be well acquainted with each of the reasons behind facing such issues while driving so that you can deal with them when it happens.
No wonder when your check engine light comes on and then it goes off by itself, you find it difficult to continue with your travel plans. But sometimes, you can prevent it from happening if you at least take care of a few most important things that cause such an issue with your car.
I have shortlisted a few reasons that are most common in causing such problems. And they are…
- Loose Gas Cap
- Bad Spark Plugs or Plug Wires
- Bad Catalytic Converter
These are the most common causes, in my opinion. However, all the 13 reasons why your check engine light comes on and off mentioned here in this guide are also important reasons behind such issues. So, take care of them the next time you face this engine warning light problem in your car.
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