Why is My Check Engine Light Flashing? | What is Check Engine Light Blinking?

What is Check Engine Light?

The car’s check engine light warns you if anything is wrong with one of the vehicle’s systems or components. A constantly flashing check engine light is a sign of a far more severe problem. Typically, it indicates that the engine is misfiring and allowing unburned gasoline to enter the exhaust system. This causes an elevation in the temperature of the catalytic converter, which may lead to serious damage.

What Does a Flashing Check Engine Light Mean?

The appearance of a flashing check engine light indicates a serious problem that must be rectified right away. The longer time you spend driving with a check engine light blinking, the greater the risk of engine damage. It often results from a misfire brought on by fuel or spark issues.

check engine light

The engine control unit of your vehicle is responsible for monitoring all of the sensors in your automobile while you are driving and calculating the data; it determines how much gasoline should be fed into the engine and at what angle the ignition should be fired.

P0011, P0016, and P0017 issue codes will be generated if a sensor’s value is incorrect for a brief period of time. If the engine control unit receives the incorrect value from the sensor many times, the check engine light will illuminate on the dashboard of your car.

The check engine light begins to flash if there is a serious enough issue from misfire to warrant it. This is to inform you that there is an issue right now that might harm the catalytic converter.

If your vehicle’s check engine light begins to blink, you should stop immediately, turn off the engine, and get to a mechanic’s shop.

Causes of a Blinking or Flashing Check Engine Light

Various reasons might cause a check engine light to blink or flash. The most frequent causes of check engine light flashing are as follows:

  • EVAP error codes
  • An internal engine issue (rare)
  • Misfires on a single or many cylinders (most common)
  • Overcharging issues
  • Problems with exhaust emissions
  • defective coils/spark plugs
  • Problem with camshaft sensor 
  • Engine overheating
  • Bad/faulty injectors
  • Incorrect EGR valve
  • Defective engine sensors (coolant, air temperature, exhaust temperature sensor, etc.)
  • Low air-fuel compression rate
  • Engine misfire
  • The faulty crankshaft position sensor
  • Trouble codes such as P0011, P0014, P0013, P0014, etc.
  • Low Coolant

Misfires are the most common cause of a check engine light flashing or blinking. However, it is not quite easy since so many diverse causes may lead to misfires.

1) Low Coolant Level

The low coolant level is one of the most common causes of check engine light flashing. When your car’s coolant level gets down than a specific level, the light starts illuminating and hence displays a warning of low coolant level in your car.

In such a situation, you need to refill the coolant. So, if the light is frequently glowing, it is a clear symptom that your car’s coolant is leaking, and you must figure out the problem.

2) Bad MAP Sensor

All the sensors in your car’s engine are continually monitored by the vehicle’s powertrain control module (PCM) while you drive. As the MAP sensor goes bad, the PCM turns on the check engine light and starts illuminating to alert the driver.

3) Bad PCM

The illuminating check engine light is a clear symptom of a bad PCM. The light could be for anything related to the powertrain. Just keep in mind that the problem is more likely with the sensor, wiring, or just about anything else.

4) Faulty Catalytic Converter

The exhaust system in your automobile has a catalytic converter, which reduces emissions. It transforms carbon monoxide and other noxious fumes into less harmful by-products.

The latest cars also have oxygen sensors. These sensors observe the efficiency of catalytic converters by inspecting the exhaust gas level.

 As the oxygen sensor observes that the exhaust gas is not being properly catalyzed, it sends a signal to the PCM, and your vehicle PCM turns on the light to alert the driver.

Read More: Symptoms and Causes of Catalytic Converter 

5) Faulty Charging System

The battery might not be the only thing that’s wrong with your car. It could also have an alternator or some other electrical component failing to charge properly, which will result in a dead engine!

Make sure you keep an eye on this area so that the charging system isn’t affected by any issues.

6) Faulty Oxygen Sensor

The oxygen sensor is a component that gets its readings from the levels of oxygen in the engine’s exhaust. If there are low levels of oxygen, then your car check engine light will start blinking.

There are many reasons why this can happen, one of which is problems with the O2 Sensor itself. If you notice a check engine light flashing on your dashboard, make sure to get it checked out by a professional.

7) Mass Air Flow Sensor

The mass air flow sensor measures the air coming into your engine. This is to make sure there is enough air for fuel. Without enough air, your car will not start, or it might stall.

If the airflow sensor stops working, the computer will signal there is a problem with the airflow sensor in your engine and lead the Check Engine light to come on.

8) Worn or Damaged Spark Plug

Your car’s check engine light may start flashing when there’s a spark plug problem.

That usually happens when you’ve got a failing spark plug slathered in oil or running too hot, causing issues with the engine operation.

However, the Check Engine Light can also activate if there are issues with your spark plug wire, coil pack, catalytic converter, etc.

Read More: Symptoms of bad Spark Plug

9) Engine Misfiring

As the engine control unit detects engine misfiring issues, it sends a signal to the check engine light, which starts illuminating and also stores the trouble code in the cylinder with the engine misfire. Use the diagnostic scanner to check the trouble code.

10) Engine Overheating

Each car will have a warning light or temperature gauge that will come on to tell you the temperature engine. If the warning light comes on, it’s saying that the engine is beyond the operating temperature.

If the temperature gauge is over the red or near the top, that is a sign of excessive heat on the engine. The only issue with these devices is that sometimes they don’t work right because of a coolant leak which causes the sensor to have nothing to read.

11) Bad EGR Valve

The check engine light may illuminate due to a faulty EGR valve. As the light turns on, it shows that you most probably have a faulty EGR valve. The EGR valves take instructions from the engine control unit (ECU). 

Read More: Signs of bad EGR Valve

12) Bad Fuel Injector

The illumination of the check engine light is one of the major signs of a bad fuel injector. Whenever the injector delivers less (and in some cases more) fuel than requirements, the engine performance reduces, and ECU turns on the check engine light. 

13) Bad EGR Sensor

When any component of the EGR system goes bad, the check engine light starts illuminating.

Read More: Signs of bad EGR Sensor

 14) Bad Crankshaft/Camshaft Position Sensor

Whenever your crankshaft or camshaft doesn’t work efficiently, the crankshaft sensor sends a signal to the PCM, which turns on the check engine light to alert the driver.

Read More: Signs of Crankshaft Position Sensor

15) Transmission Fluid

When the transmission fluid level becomes less than a specific level, your PCM turns on the check engine light, which starts flashing.

Read More: Transmission Fluid Symptoms and Causes

How to Diagnose a Flashing Check Engine Light?

Dealing with the cause of the issue is the most effective technique to get the check engine light to go off. If you take your car to a technician, he or she will be able to reset the diagnostic sensor on the car, which will result in the engine check light being turned off.

You can disconnect and re-connect the automobile battery if you wish to do it manually. One drawback of doing so is that all of the data held on the vehicle’s computer will be lost.

Flashing Check Engine Light

You have to be aware of the fact that if your check engine light is on for an extended period of time or blinks rapidly, the computer will record a trouble code in the memory. This will allow you to determine what was causing the issue.

The technique of guessing which components could be causing the check engine light and then replacing them is terrible. Almost often, doing this will result in money wasted.

The best and most efficient method is to look at what the engine control unit is attempting to communicate to us. A diagnostic scanner may be used to do this.

For example, if you receive a misfire error code as well as one relating to an ignition coil, you should certainly continue investigating that ignition coil.

If you are getting misfires on a particular cylinder, you should inspect the plugs, ignition coils, and wirings. If numerous cylinders are misfiring, it is most likely due to a mixture that is either too lean or too rich.

How much does it cost to fix a flashing check engine light?

The repair or fixing cost of flashing check engine light varies according to the vehicle model and the nature of the problem.

  1. Most commonly, the check engine light blinks due to engine overheating. The engine overheating fixing cost is between $90 to $1,600
  2. The repair cost of the flashing check engine light due to a bad crankshaft position sensor is between $170 and $210.
  3. The fuel injector replacement cost is from $350 to $850.
  4. Spark Plug replacement cost is between $20 to $110.

FAQ Section

Can I drive my car with the check engine light blinking?

It is generally recommended that you should not drive your vehicle if the check engine warning light is on and flashing. It’s a true emergency. It is usually an indication that the engine is misfiring. If you continue to drive, you will certainly do irreparable harm, mostly to the catalytic converter.

How long can you drive with a blinking engine light?

The check engine light is typically a yellow or red engine shaped icon situated in the middle of your vehicle dashboard, behind the driving wheel. Depending on the issue that triggered the Check Engine light, you may be able to continue driving indefinitely or only for a couple of days. Covering a distance between 50 and 100 miles gives the engine computer time to recalibrate certain sensors, which may solve the problem.

Is it safe to drive with a flashing check engine light?

An engine light that is blinking is quite concerning. The vehicle owner should quickly bring their car to a repair center in these situations. Taking the car there on their own may be risky for them.

What does it mean when your check engine light blinks 10 times?

It means that one or more of the emissions systems is not ready, also known as the I/M readiness test. All the systems will be tested as you drive the vehicle, and the light usually stops blinking after a few driving cycles.

What does it mean if your check engine light is blinking then stops?

Check engine light flashing frequently signifies a cylinder misfire. In order to avoid further damage to the catalytic converter and thus higher repair costs, it is critical that any misfiring be checked and corrected as soon as possible.

Will driving with misfire damage my engine?

Having faulty spark plugs or an air/fuel ratio imbalance might lead to an engine misfire. It’s dangerous to drive with a misfire in your engine, and it might even cause damage.

What does it mean “check engine light flashing” but no codes?

Usually, when the check engine light blinks, a misfire occurs. To set a code, you need a certain amount of misfires in a drive cycle.

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