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Top 10 Reasons Why Your Car's Check Engine Light Is On

Educational  ·  November 11, 2020

Top 10 Reasons Why Your Car's Check Engine Light Is On

The check engine light indicates, for the most part, the state of your car. Whether you’re leisurely cruising or rushing for an important meeting, the sight of the check engine light turning on will have the same effect on you. It will give you a good dose of scare.

The amber dashboard light will flash or light steadily. It is triggered by several factors, including low oil pressure, a loose fuel cap, overheating, or some other major engine problems.

Most Common Reasons Why the Check Engine Light Comes On

You shouldn’t ignore your car’s check engine light whenever it comes on – safe driving principles dictate. These are some of the reasons the engine light comes on. 

Loose fuel cap

A loose fuel cap is one of the reasons why the check engine light could turn on. The gas cap helps to keep gasoline fumes inside the tank. It also keeps the car’s system under ideal pressure. If the check engine light turns on after a refill, confirm whether the fuel cap is loose and tighten it up. Note that the lid can become worn out. If it's worn out, you need to replace it.

Clogged catalytic converter

A catalytic converter, which is an integral part of the exhaust system, has the primary function of converting toxic gases into harmless components. When clogged, it can trigger the check engine light. Unfortunately, you cannot prevent the failure of a catalytic converter. If it gets damaged, a replacement is imperative.

Oxygen sensor failure

Could it be oxygen sensor failure? Interestingly, your car engine will keep running even with a malfunctioning oxygen sensor. However, if you are keen, you will note that fuel consumption will increase. The oxygen sensor is part of the exhaust system. It measures the amount of unburnt oxygen and sends the information to your car’s computer. The procedure helps to regulate the amount of air and fuel that enter your vehicle’s cylinders. A damaged sensor has to be replaced.

Damaged spark plugs

Spark plug wires are essential during ignition, as they transmit electricity from the coil. Damaged wires result in poor engine performance and a drop in gas mileage, which triggers the check engine light. If the spark plugs get damaged, you have to replace or incur hefty losses. 

Vacuum leak

It could be a vacuum leak that’s turning on the check engine light. The vacuum system helps get rid of the engine of harmful fumes. More so, it is an essential part of the brake booster system of your vehicle. A leak occurs when old vacuum hoses dry up and start cracking. Also, a leak can result from loose connections.

Failure of exhaust gas recirculation

Your check engine light will automatically turn on when the exhaust gas recirculation fails. A damaged exhaust gas recirculation will need a replacement, a standard DIY procedure for most car owners. However, if the reason is clogging, you can clean the system. 

Drained battery

It could be time to change or charge the battery if the check engine light comes on. As the source of power, the battery allows you to start your car, charge your phone, keep the stereo on, and light the car headlights. These components drain the battery: that's what it's for. However, some additional parts like alarm systems could be the cause of the failing battery. Always have the aftermarket alarm installed by an expert. It could be the reason behind the check engine light. 

Mass airflow sensor

The mass airflow sensor (MAF) regulates the air entering your car’s engine. It also helps your vehicle adjust to changes in altitude. A malfunctioning MAF results in reduced gas mileage, troublesome ignition, and stalling. Additionally, it triggers the vehicle’s check engine light.

Ignition and spark plugs

Consider checking the condition of the ignition coil and spark plug. It sparks plugs that ignite the air and fuel mixture in your car's cylinders. The process is completed by electric sparks generated by the ignition coil. Your car hesitation during acceleration is an indication of damaged plugs. Defective plugs also cause engine misfires, which should be corrected before they damage other components.

Does Check Engine Light Turn Itself Off?

The check engine light turns on whenever the car has a problem. Before the underlying issue is resolved, the light will remain on. However, the check engine light sometimes turns off on itself. 

Your vehicle automatically conducts tests of its systems. When the car runs two consecutive tests and both fail, the check engine light turns on, indicating an underlying problem. Therefore, if the check engine light turns itself off, it means the car passed the automatic tests.

Final Words

No matter how careful you are, your car check engine light will turn on at some point. Unavoidable wear and tear will make some car parts malfunction and cause the check engine light to turn on automatically. If it’s your lucky, the cause could be avoidable and easy to resolve, such as a loose gas cap.

The best way to handle your car is through frequent check-ups and replacing faulty car parts. 

Concerning the check-ups, make sure to enlist the services of an experienced and trustworthy mechanic. Take note that some may be experienced but not trustworthy. When it comes to buying car parts, get the best deals through Carpart's request-a-part tool. At, you will find vetted sellers of auto parts and accessories needed to keep your car in tiptop shape! 

Be proactive – do not wait for the engine light to jerk you into action.

By Eric Anyega

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