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Why Is My Check Engine Light Flashing?

why is my check engine light flashing

The Check Engine Light (CEL), also known as the Malfunction Indicator Lamp (MIL), or the “check engine soon light”, is a warning light in your car. When this light flashes, it tells something about your car; informing you of malfunction inside the vehicle’s system that needs to be addressed.

But you shouldn’t panic when you see the check engine light illuminates. Instead, you should be cautious enough to find the source of the problem. The CEL is part of the vehicle’s onboard diagnostics system (OBD) and the engine control unit (ECU) is in charge of the various parameters. If these monitoring systems get reading/s (or find fault) that’s out of the ordinary, the check engine light pops up.

This article will explain to you the role of this warning light and will surely answer your frequent question on ‘why is my check engine light flashing’?

What is a Check Engine Light (CEL)?

The Check Engine Light is mostly found on the instrument panel of vehicles. The light usually bears the legend ENGINE, CHECK ENGINE, EMISS MAINT, SERVICE ENGINE SOON, MAINTENANCE REQUIRED, or a graphic representation of an engine (see Figure 1) with/without the word ‘CHECK’ below.


When this light is illuminated, it is commonly yellowish, brown, golden, or red in color in some vehicles. The light is quite easy to distinguish from other warning lights on the dashboard. When this indicator lamp is lit, the ECU stores a fault code related to the problem. The codes could be retrieved, though, but for some car models, it usually requires a scan tool. If you want to find the best car scanner, read this.

The CEL varies in appearance from car to car, but it has the same basic meaning; to tell you that something is wrong with your car. 

Your car’s computer system regulates and monitors the automobile’s performance controlling parameters such as ignition timing, fuel mixture, speed (RPM), and other variables. The computer can also tell you when to shift the automatic transmission

So, what does a flashing check engine light mean? Keep on reading.

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Two Stages of Check Engine Light

  • First Stage: Steady

When the check engine light illuminates steadily, it usually indicates a minor fault or problem. But it still needs immediate attention. You should schedule an appointment with your most trusted mechanic as soon as possible. One of the most common reasons for a steady illumination of the CEL is a loose fuel cap, 

  • Second Stage: Flashing

When your check engine light keeps flashing or blinking, it indicates that there is a severe engine misfire where unburned fuel is dumped into the exhaust system. This may increase the temperature of the catalytic converter.

Once the temperature rises, the converter might be damaged that may require expensive repair. To avoid damage to the converter, you must reduce power and let your vehicle checked by a qualified technician.

A limp mode may also trigger the flashing of the warning light.

Other reasons why ‘my Check Engine Light is flashing’?

There are so many possible reasons that may trigger the check engine light to flash (depending on your car brand and model, make, and year). The warning light mostly illuminates due to problem/s on your car’s emission system, but the check engine light can indicate almost anything from a loose cap to a severe knock on the engine.

reasons why ‘my Check Engine Light is flashing’

Here are some other reasons why your Check Engine Light is flashing:

  • Dirty or sticky exhaust fume recirculation valves
  • A busted gasket head
  • Malfunctioning oxygen sensors
  • Cracked or loose manifolds or hoses
  • Cramped or nipping fuel injector O-rings
  • Bad spark plugs or spark plug wiring
  • A moisten or wet engine.
  • Failing catalytic converter
  • Failure of the mass airflow sensor
  • A vacuum leak
  • A dead battery.

And the list goes on. You may check your vehicle’s owner’s manual for its check engine light faults or you may ask your dealer about this.


What to do when Check Engine Light flashes?

The computer systems of today’s automobiles are designed to give an outlook on the vehicle’s performance. The computer works hard in trying to compensate when a problem or troubles arise. If your check engine light is flashing, look for problem/s that may require attention as soon as possible.

Here are just some actions that you may do when the check engine light comes on flashing:

  • Check your fuel cap

This is one of the major causes of why your check engine light will come on, especially if you have a new car. Sometimes people forgot to check if their fuel cap is on after refueling. In some instances, the gas cap is not tight enough. So, when your CEL gleams, try tightening first your fuel cap. 

Make sure your gas cap is in the proper place and is tightly secured into the tank. Sometimes, this solves the problem of an illuminating check engine light.

  • Reduce your speed and load

If the check engine light is flashing and you are experiencing an engine performance problem (like a loss of power), especially when you are towing another vehicle, slow down and find a good place to pull over.

Once you stopped in a safe place, try to reduce your load by stop towing the trailer. Then, have your vehicle checked by a qualified mechanic or technician for a possible problem

  • Read the code and try to fix the problem

If you are not adept at reading a car scanner, you can always seek the help of a professional. But in case you can crack the code on your OBD system, you may know the reason why the check engine light flashes.

In this case, unless there is an immediate solution to the problem, it is better to let your car diagnose by a professional technician. Most automotive parts stores have the right tools to read and interpret the code for you. Then, make the right solution to solve the problem, which will avoid more expensive repairs when not addressed immediately.


Knowing what is happening to your car will spare you from more expensive repairs when you suddenly realized that your check engine light flashes. A check engine light flashing tells more stories than you ever realized; so don’t ignore this warning sign, which a simple Check Engine Light could tell.

We also recommend that you buy or own some tools that could make your driving life more convenient. These tools, like a car diagnostics coder (for your OBD2 system) and a car scanner, can be a part of better maintenance to spare you from costly repairs once the problem is misdiagnosed or ignored. 

These tools also tell you how serious the problem is, so you can make the right decision.


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