Can Check Engine Light Turn Itself Off? – YES

At least once in a while the check engine light turns on. This could be due to some technical failure. But, what happens if you had your light ON for some time and then it turns off? Can it do that?

Can Check Engine Light Turn Itself Off - YES

Can Check engine light turn itself off? – Yes ”The answer is Yes. When some car system fails to pass a test the check engine light turns On. It takes 2 failures for the light to turn on. After your car has failed to pass those 3 test, it takes 40 passes in order for the light to turn itself off.”

Let’s get more into that:

Can Check Engine Light Turn Itself Off?

The reason why the check engine light comes ‘on’ is  because the car has failed some type of test. Whether that is a continuous monitor like misfires, or engine timing, or non continues monitor like the catalyst or the EVAP system, or air fuel ratio. That kind of stuff. So, it runs all these tests and when it sees a problem, it fails the test. For the most part it has to fail these tests two times in order for the light to actually illuminate telling the driver there’s a problem. Now, one failure us as technicians we can go in with our diagnostic equipment and we can look at that and see that. We can see that the light is ‘on’ and we can get the code generally, not always but generally with one failure. But in order for the light to come on, it does take two failures which is called a two trip monitor.

Why Is My “Check Engine” Light On?

Why Does The Check Engine Light Turn Itself Off?

So, let’s say that your check engine light is on and you take your car to the mechanic. The mechanic takes your car out for a ride and comes back with the check engine light turned off. Why does that happens? Well, at some point that car has passed the test three times. It takes three times of passing these tests, whatever tests had failed, will turn the light off. At this point you might feel that maybe you don’t actually have an engine problem, but it’s best if you let the mechanic to run some diagnostics. Even with the light turned off, the technicians can see which test has failed and why the check engine light was turned on in the first place.

Is It Safe To Drive With Check Engine Light On?

If nothing seems to be wrong with the engine, transmission, or the way the car is driving it means that a non-evasive sensor has failed or a simple mechanical failure is present such as a vacuum leak has occurred, you can then continue driving without additional damage to any components.

This is because the computer is equipped with predetermined values for each sensor which enables the engine to keep running without issue. This computer mode is called ‘limp mode’. This gives you time to get the car to the repair garage or to read the codes yourself and perform repairs to help save you money.

Why The Mechanic Isn’t Able To See The Issue

Sometimes the mechanics are not able to tell you what your issues is. What Audi and Volkswagen do, after 40 passes of the same test, both the light is off and the error code is gone. After your car performs 40 tests and they all pass, the mechanic could run diagnostics but he won’t be able to see any errors.

Can I Diagnose The Problem Myself?

Yes, you can do that. But, in order to do that, you will need an OBD scanner. You will have to connect this scanner to the cars main computer which is pretty easy. This type of scanner is connected to your mobile phone and you will receive the error codes on your mobile phone.

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Here are some of the most common error codes that you will get:

  1. Oxygen Sensor Code: P0171-P0175. This error code appears when you have a faulty oxygen sensor. This sensor monitors the amount of oxygen in the exhaust and gives this information back to your engine computer so it knows how to adjust the fuel mixture.
  2. Engine Misfire Code: P0300-P0305. This is a very common issue as well. This happens when one or more cylinders are not functioning properly. The mechanics work on these issues on a daily basis. The OBD Scanner is able to diagnose this issue without a problem.
  3. Evaporative System Code: P0411, P0440, P0442, P0446, P0455. The EVAP has a mission to contain and remove vapors that are created when fuel is burned. Even a loose gas gap that allows the vapors to escape from the fuel tank can trigger this failure code.
  4. Exhaust Gas Recirculation Code: P0401. The EGR controls the emission of smog from the engine. This could be if you don’t change your engine oil on time or you drive your car on short trips without warming it up which will cause carbon buildup.
  5. Catalytic Converter Code: P0420, P0430. This device converts the toxic gases into less toxic pollutants. This is a very important part of the vehicle, but will eventually become worn out and will have to be changed.

Was this article helpful? Tell us about your issues in the comment section below.

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10 thoughts on “Can Check Engine Light Turn Itself Off? – YES

  1. By far the most intuitive answer on the internet. Thank you so much! Perfect amount of information about how and why the light turns on, and then how and why the light turns off. Sounds simple enough but the other guys had my head spinning with useless or incomplete nonsense in an attempt to impress the reader. What impresses consumers is clear and concise information. Mission accomplished…! Thanks again! You have a new subscriber.

  2. my check engine comes on for 1 minute and goes off then comes back on and then goes off but some time it stays on for longer 92 saab turbo 900 161,200 miles and it starts to stumble ,new coil , new fuel pump, pump relay , new regulater, put some new vacume hoses,and coil relay any sugestions?

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  4. thanks found this to be very helpful because my check engine light keeps coming on then after 3 or 4 days it goes off so I know know now that one of these is the problem so when the time comes I have a idea what the causes it and will let you know what repair was needed when that time comes

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  8. Every two or thee months, my check engine light will come on and go out after a few hours. Usually, the light goes out once I’ve purchased new gas. Condensation seems to be a major reason my my check engine light comes on and later goes out.

  9. Thank you, Really though, we need to stop this bullshit. I donated a perfectly awesome 2001 Toyota Sequoia because I could not afford the ’emissions bullshit’ to get updated tags. This is all bullshit. We are emissions sensor slaves for no reason. There is no environmental impact from a car that has a sensor fail. It is all a scam. Maybe someone like me or maybe me, should start an auto company on 1975 tech so that we can fix our own cars again. FU epa.

  10. I have a 2011 Chevy equinox. I took it to the dealership to have diagnostics ran. They said they cannot get my check engine light to turn on? I have had the car for 2 years and the light has never worked, it doesn’t even come on when I start my car like the others do? So they told me until I can get it fixed they cant do a full scan. I have crankshaft sensors that need relearned but they said that it’s unable to be done due to no check engine light availability? They were able to do basic scans to tell me basic things that need fixed like fuel pump, pretensioners in seat, and control arms and ball joints. How do I possibly fix this check engine light issue without breaking myself 🤦

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