Check Engine Light On: Why? What to do?

Check engine light

When Check Engine Light pops up while you are driving what do you do?

Do you pull over to check your car with an OBD2 car diagnostic tool or drive directly to a mechanic shop?

Well, it’s agreeable that Check Engine Light is unsettling.

However, many average car owners have little to no clue on what the red-yellow light is telling them. Even more bustling is how to react when the Check Engine Light is on.

Essentially, Check Engine Light is the most misunderstood warning lights. This is because it could be pointing to dozens of possible problems.

On the other hand, ignoring the check engine light is certainly not an option. A failure to address check engine light can amplify the existing problem leading to costly repairs.

It, therefore, means that addressing the check engine lights should be a top priority.

What Does Check Engine Light Mean?

Check Engine Light is an essential part of a vehicle’s OBD system.

The onboard diagnostic system control as well as monitor your vehicle’s performance.

This system controls variable such as fuel mixture, engine speed, and transmission functions.

When an onboard computer identifies a problem that it can’t automatically correct, the check engine light comes on.

Check engine light can be displayed as check engine, check powertrain, or service engine soon.

It, therefore, means that you should check your car or have it checked by a mechanic when Check Engine Light pops up.

The onboard computer stores diagnostic trouble codes in its memory every time the check engine light comes on.

The code can be retrieved using an OBD2 scanner.

Flashing Check Engine Light

When you are driving and suddenly the Check Engine light comes on and blinks without stopping, what’s the implication?

It means that the onboard computer has detected a serious problem that needs immediate attention.

When this happens you should immediately pull over and have your car towed to a mechanic shop.

Having your car towed will cost you some money but it prevents the amplification of the problem that is already evident.

What cause the check engine light to flash?

Engine misfires is a common cause of flashing check engine light.

When the engine misfires it often dumps fuel that is unburned in the exhaust system.

This is a serious problem that can damage various components of the engine.

Engine misfire is often accompanied by the temperature of the catalytic converter being raised to a level that it can damage the converter.

Replacing catalytic converter can cost you an arm and a leg.

It is therefore advisable to immediately pull over when you notice the flashing Check Engine Light.

Also, Check Engine Light can blink or flash if you crack your car’s manifold gasket, or if you have a misfiring cylinder, or there is a bad coil.

The bottom line is that flashing check engine light is an indication of a serious problem.

Pull over and have your car towed so as to be checked and diagnosed as soon as possible.

Steady Check Engine Light

In this case, Check Engine light can pop up and stay steady on the dashboard.

Steady check engine light in most cases should not cause panic.

How should you react when you see this steady check engine light?

It means that your car needs to be serviced.

If you are a DIYer you can use an OBD2 scanner to diagnose the possible problem.

Simply put, steady check engine light is not an indication of an emergency situation.

However, you should diagnoses the car as soon as possible.

Common problems that cause check engine lights to come on.

What are the common causes of the check engine light?

Loose Gas Cap

Gas cap plays an important role in sealing the fuel system as well as maintaining a steady pressure in the fuel tank.

Besides, it prevents the emission of gasoline into the environment whenever your car is parked.

loose gas cap

Failure to replace or tighten a gas cap can lead to fuel loss.

You need to tighten your gas cap. If the gas cap is misplaced you need to get a new one.

Malfunctioned oxygen sensor

New vs old oxygen sensors (4144783963)


The oxygen sensor is designed to measure unburned oxygen that is exiting from the exhaust of your car.

If you do not replace the defective sensor then the engine will burn more fuel.

You may lose up to 40% of fuel, or even worse damage other engine components

Failing spark plugs and wires


Spark plug delivers a spark for effective fuel combustion.

When you fail to rectify the problem you may experience a reduced power and lead to fuel wastage.

It may also contribute to clogging of the catalytic converter.

Defective catalytic converter


After scanning the car and verifying this problem, you should have a mechanic replace the defective catalytic converter immediately.

Catalytic converter plays an important role in converting carbon monoxide into harmless carbon dioxide.

You should not drive your car when you experience this problem.

Let it be towed to a mechanic shop and have the problem fixed.

Malfunctioned mass airflow sensor

Bosch Mass Air Flow Sensor location in the engine bay (Opel Antara 2.0 CDTI)


Mass airflow sensor plays an important role in determining the appropriate amount of air needed to burn engine fuel.

The OBD2 scanner can accurately pinpoint this problem. You need to replace the sensor.

A failure to address the problem can cause damage to other engine components.

Some of these components include the catalytic converter, O2 sensor, and spark plugs.

Is it safe to drive with the Check Engine Light on?

The first thing that comes to mind when the check engine light comes on is whether it is safe to drive with check engine light on.

When the flashing check engine light comes on you need to pull over immediately.

Such a move is critical in ensuring that you do not cause further damage to major components of your car

Damaging major components such as the catalytic converter can significantly add to repair cost.

Have the car towed immediately to a mechanic shop for inspection.

A mechanic will use an OBD2 scanner to establish the source of the problem.

However, when the check engine light comes on without blinking you may need not to pull over and have the car towed.

What you should do is to drive to a convenient place, be it a parking zone, home, or to a mechanic shop and have the car diagnosed.

If you are a DIYer you can use an OBD2 scan tool to diagnose and fix the problem.

What to Do About the Check Engine Light?

Undoubtedly, when you have Check Engine Light on, you need to perform a diagnosis.

You have two options when faced with Check Engine Light.

If you are a DIYers or a car enthusiast, you can diagnose the car yourself.

On the other hand, you can drive it to your mechanic.

Whichever option you choose, OBD2 scanner plays a major role in diagnosing your vehicle.

Turn the Check Engine Light Off with an OBD2 Scanner

MaxScan OE509 img95


Once you have fixed an existing problem, use an OBD2 scanner to turn off the Check Engine Light.

The OBD2 scanner will connect to your vehicle onboard computer and you can turn off the CEL by pressing the clear button.

You could be wondering where to get an OBD2 scanner.

The good news is that there are many OBD2 scanners for average car owners, DIYers, mechanics, and professional techs.

Better yet, you can get an incredibly cheap OBD2 scanner that performs both basic and advanced functions.

All you have to do is choose OBD2 code reader that you can comfortably use to turn off the Check Engine Light.

Visit your mechanic

The second option involves visiting your mechanic.

The advantage of taking your car to a mechanic is that the mechanic can diagnose your car using a professional OBD2 scanner and fix the problem.

Bonus: 10 Best Professional OBD2 Scanners Review and Comparison 2021

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