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The Dreaded Check Engine Light

why is my check engine light on

The Check Engine Light is a yellow or amber color that illuminates your dash to indicate there is an issue with your engine. Not only is it a worry but it is highly frustrating as there is no indication to what the problem even is.

In order to understand why your car is flashing the warning, you will need a check engine light OBD2 scanner that will pinpoint the issue and provide you with a short explanation and a code.

If you are pulled over to the side of the road right now with the error, do not panic and call a tow truck immediately. Unless there is fluids pouring out the vehicle, components missing or any horrendous issues, you should be okay to drive to a safe location. Of course, this is at your own risk but many people will drive thousands of miles with the check engine light on because they know the severity of the problem.

How To Turn Off Check Engine Light

In order to turn off your check engine light, you have the following 4 options.

  1. Use an OBD Scanner.
  2. Disconnect and reconnect the battery.
  3. Turn the engine on and off a few times.
  4. Drive the car gently for a couple miles.

The first option of using an OBD scanner is the safest and most popular method. However, it will cost as you will need to purchase one for yourself or go to a garage who will plug it into their own code readers. Once connected, you will be able to scan your vehicle for any errors, read them and choose to remove them. Once this process is complete, redo the scan to see if there are any still present. If there is, you would have identified the issue and if there isn’t, the check engine light should not be appearing anymore.

Disconnecting the battery for a few hours or over night is a good and FREE option to trial. It has the effect of clearing any data in the vehicles memory but be sure to keep check of your stereo security key as it normally removes this data too.

Turning the engine on and off a few times has the effect of resetting the vehicles computer in some cases. It is a similar method you would use for your internet by resetting the router. However, from previous experience, the two methods above are the most effective.

Driving the car until the light goes off is sometimes works as some issues have the tendency to fix themselves. For example, you may have used the wrong octane fuel in your car or having DPF issues that required a drive to clear.

check engine light symptoms

Why is my Check Engine Light On?

All gasoline/petrol vehicles require three aspects to work correctly, these are air, fuel and a spark. If you take one of these away, you are going to run into issues with your vehicle. Not forgetting diesel vehicles, these will require a similar aspect apart from the spark.

So that being said, why is my check engine light on? Below are 10 common reasons:

  1. Incorrect fuel put into the engine i.e. 91 Octane instead of 98.
  2. Catalytic converter failure.
  3. Mass airflow sensor is faulty (incorrect air to fuel ratio).
  4. DPF Clogged.
  5. Oxygen sensor faulty.
  6. Turbo Issues.
  7. Loose gas cap.
  8. Vacuum leak.
  9. EGR valve failure.
  10. Spark plugs not igniting.

Of course, all vehicles are different and some may react differently to certain issues. It is quite common that some people will mistake a service light for a check engine light and worry themselves over nothing.


When you see the Check Engine Light for the first time, your first instinct is to freak out. However, do not worry until you have actually diagnosed the issue with the car because it may be something very minor. We highly recommend that you buy yourself an OBD2 reader as you will save money from not going to visit your local mechanic each time it lights up.

procarreviews author

Written By Dan

About the Author

Dan is an automotive journalist and owner of over 10 cars ranging from supercars, tuned cars, classics and your good old beater cars. He always likes to get his hands dirty with nut and bolt restorations or detailing sessions using the best products on the market.

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