Flashing Check Engine Light: Causes, Risks, and Solutions

Flashing Check Engine Light: Causes, Risks, and Solutions

February 20, 2024 0 By CarGuy

Although many people hate it, the flashing check engine light is one of the most vital indicators in your car.

Every time this light illuminates or flashes, it means that your car has a problem and this problem has to be sorted out as soon as possible.

So, in order to help you out, we will dive deep into the root causes, potential risks, and solutions for this problem when you experience a flashing check engine light. So, buckle up because it will be a long ride!

Flashing Check Engine Light Basics

The check engine light is one vital part of the car’s OBD system. This light is connected to the ECU of the engine.

The ECU is the brain of the car that regulates every sensor and the work of the engine. So, whenever the ECU notices a problem, the check engine light will illuminate or flash like in this case.

This is why we advise that you don’t ignore the light on the dash and make sure that you address the problem as soon as possible.

This light can mean many things and only proper diagnostics will tell you what is really the root of this issue.

So, in order to help you out, we will list some of the potential causes of this light and see what could be triggering it.

Causes of a Flashing Check Engine Light

Let’s learn some of the potential causes for the flashing check engine light.

1. Ignition Problems

Probably the most common reason for the flashing check engine light is ignition problems.

The ignition system has a lot of components that can go wrong. But the most common ones to fail and show this problem are the spark plugs and coils.

Spark plugs can foul from coolant or engine oil. Or simply fail because of age.

While ignition coils that sit on top of the spark plug can fail or malfunction. In this case, you will also get a check engine light.

In older cars, the distributor can also fail and cause such a problem.

And when you have such a problem, you will also experience engine misfires.

2. Damage To The Catalytic Converter

The second most probable cause for this problem to appear in your car is the damage done to the catalytic converter.

For those who don’t know, the catalytic converter is an emissions device and each car has a minimum of one and a max of two of these devices. One per each bank in V6 and V8 engines.

What can happen is when the engine has some internal problems such as oil consumption and misfires, the catalytic converter can clog up.

In this case, you will have a flashing check engine light. So, you must make sure that the catalytic converter is in good condition.

3. O2 Sensor Failure

Another very common cause for this problem with the flashing check engine light is an O2 sensor failure. So, what is an O2 sensor?

This type of sensor is installed on the exhaust. There is one before the catalytic converter and one after the catalytic converter.

This sensor measures the flow of exhaust gasses and helps the computer adjust the air-to-fuel ratio.

If one of these sensors malfunctions, you will get a steady glow check engine light or a flashing check engine light.

4. MAF or MAP Sensor Failure

A problem with the MAF or MAP sensor can also trigger such a problem with the flashing check engine light.

These two sensors are not the same but have similar roles. Some cars have MAF, some have MAP, and some have both of these sensors.

Basically, they measure the volume of air injected into the intake manifold.

This helps the engine adjust the air-to-fuel ratio. If one of these sensors is broken, there will be a check engine light and other running issues.

Sometimes cleaning the MAF with compressed air helps solve this problem.

5. Loose Gap (EVAP Problems)

Something like a loose gas cap can also cause such a problem to appear in your car. So, why is this the case?

The gas cap is an integral part of the EVAP system. It has to be always tight and seal well.

If it doesn’t seal, you will have a check engine light and a DTC code.

A tear in the vacuum lines of this system can also cause such a problem, as well as a bad purge valve solenoid or a bad vent valve solenoid.

Risks Associated with a Flashing Check Engine Light

Now let’s take a look at the potential risks of running your engine like this in the long term.

1. Engine Damage

One of the biggest concerns of ignoring the flashing check engine light is engine damage.

This is a problem that should not be ignored because other things in the engine can go wrong.

Let’s take for example the O2 sensor. This component is vital for your catalytic converter to work properly.

If you have a malfunctioning O2 sensor, your catalytic converter could fail. And for those who don’t know, catalytic converters are really expensive. Often costing up to $2,000 to replace in some models.

2. Poor Performance

The second reason why you should not ignore this problem is the poor performance that your car will deliver.

You will instantly notice how the car is down on power and that something is not right. This is the case because the computer is not able to adjust the work of the engine or the car simply goes into limp mode.

A limp mode is a situation where your car reduces the RPM and limits the engine performance.

And driving like this will also make your car consume a lot of fuel in the process.

3. Safety Hazards

Potential safety hazards can also happen if you drive such a car that has a flashing check engine light.

By this, we mean that the car could stall all of a sudden and put you in some potentially dangerous situations, especially on the highway where cars drive at great speeds.

4. High Repair Costs

High repair costs are also something that is expected if you delay the repairs. So, why is this the case?

Well, let’s say that the engine is misfiring, you have a bad ignition coil that is triggering this check engine light.

This means that the cylinders are not firing in the right order, so your car will run poorly.

This will take bad fumes into the exhaust, specifically in the catalytic converter, and cause the catalytic converter to fail.

This will result in a very expensive repair. The same story goes for the O2 sensor as we noted previously.

This is why you should not delay the repairs on your car.

5. Impact On The Environment

The environmental impact will also be pretty big compared to a car that works normally.

Your car will pollute a lot more and you will also fail the emissions testing. And you definitely don’t want that to happen.

So, tackling this issue on time is the best thing you can do to avoid any potential problems down the line.

Solutions for Addressing a Flashing Check Engine Light

Now let’s take a look at the potential solutions that you need to get to solve this problem.

1. Book A Diagnostics Inspection

If you are new to cars and you don’t know how what to do in this situation, your best bet would be to book an inspection.

There are a lot of shops that are experts in tackling such problems. They will diagnose your car in a matter of minutes.

This way, you will not have to worry about anything. Let them do the job, replace faulty components and your car will be as good as new.

2. Grab An OBD2 Scanner

If you are a DIYer, we can recommend that you get an OBD2 scanner. An OBD2 scanner is a diagnostics tool that will allow you to get access to the OBD port.

Just plug the connector in the OBD port of your car and let it scan for codes.

You can first clear the codes and then repeat the scan. The codes that stick are causing your problem.

Then based on the codes, you can move on and troubleshoot certain components.

For example, the O2 sensor, MAF Sensor, spark plugs, and coils. It depends on the DTC codes that you have.

3. Replace The Faulty Components

Troubleshooting is done with a multimeter. With a multimeter, you can inspect the component and measure its properties.

That’s how electrical components are checked for problems.

The last step in the process will involve replacing the faulty component with a new one and clearing the codes.

Once the component is replaced, the check engine light will disappear.

Conclusion To Flashing Check Engine Light

The flashing check engine light is a clear indication that you have some kind of a problem with your car.

That’s why ignoring it will not do anything good. It can result in a more expensive repair, as well as some safety hazards.

This is why we recommend that you take your car to the nearest diagnostician to take a look. Then based on the input, replace the faulty components and the problem will be successfully overcome.


What are the common causes for the flashing check engine light?

There could be many different causes behind this problem. For example, there can be problems with the ignition system, such as bad spark plugs and coils, problems with the O2 sensors, catalytic converter, and EVAP system.

How to solve a flashing check engine light?

Solving this problem will require deep diagnostics with an OBD2 device and testing the potential problematic components, such as the sensors or ignition coils depending on what is causing the problem.

If you want to read more about a similar problem, you can check our article about the blinking check engine light and oil on spark plug.