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Check Engine Light On and Off Intermittently: Why Is It Happening?

What Does Fault Code P0705 Mean

It’s one of the worst things about owning a car. You’re driving down the street when suddenly, out of nowhere, the check engine light comes on. You start to panic almost right away as you dream up worst-case scenarios in your head and try to calculate how much it’s going to cost to fix your car so that you’re able to get the check engine light to shut off. But then, just as quickly as it came on, the check engine light shuts off. For a little while at least. And you’re forced to deal with a check engine light on and off intermittently for no logical reason.

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This can be very frustrating for those who own vehicles. They’re not usually sure what they’re supposed to do when they have a check engine light on and off intermittently. If you’re going through this now, you should learn more about what might be happening. It’ll help you get some semblance of control over the situation so that you can fix the problem once and for all. Continue reading to find out more.

What Is a Check Engine Light?

Before we begin talking about why you might be experiencing a check engine light on and off intermittently, let’s make sure that you know what a check engine light is. Most car owners have, unfortunately, seen the check engine light come on in their cars at least once or twice. But there are still some people who may not have had the pleasure of seeing it just yet.


The check engine light, which is also sometimes referred to as the malfunction indicator lamp in some circles, is a yellow or orange light that will appear on your car’s dashboard when your car is having a problem. It’s shaped just like an engine and will often have the word “CHECK” or even the words “CHECK ENGINE” under it. It’s pretty much impossible to miss it.


Contrary to popular belief, the check engine light does not always mean that there is a serious issue with your engine. But it does usually indicate that there’s something happening with your car that you’re going to need to fix sooner rather than later. It’s why you shouldn’t ever ignore a check engine light, even if you have a check engine light on and off intermittently. You should always find out what has caused it to come on by taking it down to your local mechanic so that they can look at it.

What Causes a Check Engine Light to Come On?

Now that you know what you should be looking out for as far as your check engine light is concerned, let’s get into talking about what can cause a check engine light to come on in the first place. There are quite a few things that are going to force your car’s check engine light to come on. Some are very serious problems, while others are less serious in nature.


Here are some of the most common car problems that will lead to a check engine light coming on and staying on:

  • Bad ignition coils
  • Bad fuel injectors
  • Bad thermostat
  • Bad evaporative emissions purge control valve
  • Bad evaporative emissions purge solenoid

More often than not, you’re not going to have a check engine light on and off intermittently when you have one of these issues going on. They’re going to cause your check engine light to come on and stay on until you address whatever is happening under your hood.

What If a Check Engine Light Is On and Off Intermittently?

If you have a check engine light on and off intermittently, you probably don’t have to worry about any of the problems that we just mentioned. Those issues are all typically going to keep your check engine light on for the long haul. There are, however, some car problems that are going to have your check engine light randomly turning on and off at different times. You might not see the check engine light on for a week or two and then suddenly have it turn back on when you’re going through one of the following problems.

1. Loose Gas Cap

Yes, believe it or not, a check engine light on and off intermittently could be caused by something as simple as a loose gas cap. If you don’t tighten your gas cap all the way while putting it back on, it could lead to your check engine light coming on. And it’s going to stay on until the next time you go to put gas in your car and tighten it properly.


Your gas cap might also cause your check engine light to come on and off intermittently if there is something wrong with it. If there is an issue that’s preventing you from being able to tighten it like you should, that could result in your check engine light popping on and off at times since your car’s main computer won’t be able to tell what’s happening.


You should try to get into the habit of checking your gas cap first anytime your check engine light appears. By tightening it, you might be able to get your check engine light to go off. It’s easily the quickest fix for a check engine light on and off intermittently.

2.  Faulty Oxygen Sensor

In a perfect world, you’ll find that a check engine light on and off intermittently is being caused by a loose gas cap. It’s obviously one of the easiest car problems to remedy without spending too much time or money on it. But many times, a check engine light will be caused by something other than a loose gas cap. It can, for example, be caused by a faulty oxygen sensor.


The oxygen sensor in your car is in charge of making sure your engine gets the right amount of oxygen at all times. This oxygen is mixed with the gasoline in your car to keep your engine going. If there isn’t enough oxygen, the combustion process won’t be able to play out like it’s supposed to in your engine. If there’s too much oxygen, it can lead to damage being done to your engine. It’s important for your oxygen sensor to help provide the right mix.


If your oxygen sensor isn’t working right, it’s going to throw everything in your engine off and lead to your check engine light going on. But your check engine light might also come on and off over time if you don’t get your oxygen sensor fixed. When you have a check engine light on and off intermittently, it might lead you to think that the issue isn’t a big deal. But a faulty oxygen sensor is a big deal and needs to be dealt with accordingly.

3. Bad Spark Plugs

Have you noticed that your car doesn’t start up quite like it used to? Or do you sense that your car isn’t accelerating in the same way that it once did? These things can both be caused by spark plugs that have gone bad. Worn-out spark plugs can affect your engine’s combustion process and throw it all out of whack. It can also lead to a check engine light on and off intermittently.


The thing about bad spark plugs is that, initially at least, you’re going to be able to continue to drive around with them. They’re not going to completely prevent you from starting your car up and driving it. But as they get worse and worse, you’re going to see the problems with your car pile up. It’s why you shouldn’t turn a blind eye to a check engine light on and off intermittently due to bad spark plugs.

4. Faulty Mass Airflow Sensor

As you drive your car down the road, air from outside of it passes through your air filter and makes its way towards your engine. There is what’s called a mass airflow sensor in place to measure exactly how much air is getting to your engine. It’s designed to prevent too much air or not enough air from reaching the engine, and if it goes bad, it’ll sometimes lead to reduced fuel economy. It’ll also lead to a check engine light on and off intermittently.


This is yet another car problem that you should not ignore, even if it doesn’t always cause your check engine light to be turned on. Outside of causing your car to burn through more fuel than it should, a faulty mass airflow sensor can also do damage to parts like your spark plugs, your oxygen sensor, and possibly even your catalytic converter.

What Should You Do If Your Check Engine Light Comes On?

If your car’s check engine light comes on, there is going to be a part of you that will want to ignore it. There are actually some people who will go through the trouble of trying to shut their check engine lights off without ever bothering to fix whatever problems caused them to come on in the first place. As we alluded to earlier, check engine lights have been putting fear into the hearts of car owners for years now.


But you should resist the urge to do this and instead seek the services of a mechanic so that you can get to the bottom of whatever is causing your check engine light to come on. They could use a special tool to pull codes from your car’s main computer that will tell them what’s wrong with your car. Whether you have a loose gas cap causing your check engine light to come on or a faulty mass airflow sensor, they’ll be able to figure it out within just a few minutes.


From there, you should then seek to fix whatever the issue is with your car with the help of your mechanic. No one enjoys paying for expensive car repairs to be done to their vehicles. But if you don’t make the necessary repairs to your car, your check engine light might end up staying on for more than just the original reason. It won’t be long before the car problems that you’re experiencing begin to pile up on you.

Should You Ignore a Check Engine Light If It Turns On and Then Shuts Off?

If you have a check engine light on and off intermittently, you might think you’re in better shape than someone with a check engine light that’s always on. That means that your car isn’t in that bad of shape, right? Wrong! The truth is that the problems that you’re experiencing could be just as bad, if not worse, as the problems that someone with a check engine light that is consistently on is experiencing.


The only difference is that, for one reason or another, your car’s main computer might not be registering the problems at all times. You might have, say, an oxygen sensor that appears to be working properly at some points and then not working properly at other times. It can cause a check engine light on and off intermittently.


Even still, you’re not going to want to take your foot off the gas, so to speak, when it comes to getting your car fixed. You should avoid relaxing when your check engine light goes off and continue to push to get your car fixed ASAP. It’s the only way you’re going to get a check engine light to go off and stay off for good.

Can You Sell a Car When Its Check Engine Light Is On?

If your car has a check engine light on and off intermittently or if your car has a check engine light on all the time, you might be finished and done with it. You might want to sell it as quickly as you can so that you don’t have to deal with the problems that you’re having with it anymore. But can you do this?


Under normal circumstances, you may struggle to sell a car with its check engine light on to a private buyer. But you can do it rather easily when you sell it to a company like Cash Cars Buyer. We’ll take your old car off your hands, check engine light and all, without asking any questions. We’ll pay you top dollar for it, too. Contact us today to discover what your car could be worth at this time.

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