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7 Symptoms Of A Bad Spark Plug



Spark plugs are important maintenance items that should not be overlooked or neglected. They play an important role related to engine performance, fuel mileage and exhaust emission standards.

The spark plug is responsible for creating the electricity that ignites the air-fuel mixture in the combustion engine, which starts your car.  Appropriate and timely maintenance not only improves the longevity of your vehicle, but it also creates a better driving experience.

If you forget to take your car in for a regular tune-up, it may begin to show signs that it needs some attention. Here are some symptoms that let you know it’s time to replace your spark plugs.

Your Car Doesn’t Start Easily

If you have trouble starting your car, and you are sure it is not a battery problem and your car is not out of fuel, it might just be a bad or worn out spark plug.

A bad or worn out spark plug does not produce the spark needed to get the vehicle moving. If this happens, your car won’t start. A faulty spark plug can drain your car battery.

Lack of acceleration

When your car does not accelerate when you put your foot on the accelerator, this is also a sign of a bad spark plug. This ‘sluggishness’ can be easily fixed by having the vehicle serviced with a spark plug change.

Your engine constantly misfires

A car engine misfires when it causes the moving car to suddenly halt – for a fraction of a second – and then resumes normal motion.

When this happens, it means one or more cylinders are not firing properly. This condition can lead to higher petrol gas emission or the burning of more fuel.


Engine Gives Inconsistent sound

The sound originating from the engine is consistent and smooth. But if your spark plugs are not performing as they should, your engine will produce a rough and jittery sound while producing larger vibrations through the car. Not having this checked can lead to costly damage being done.


Prevent cracks in your windscreen from spreading

Never ignore cracks or chips when you discover them on your vehicle windscreen. Some cracked windscreens are often the result of a chip that was left unrepaired and then grew into something more serious. Some cracks – when discovered early – can be prevented from spreading.


Engine surging

When your car jerks and then slows down, or it constantly starts and stops, this could be a sign of a bad spark plug.

Jerking or surging occurs when a vehicle sucks in more air than usual in the combustion process. Jerking can cause a car in motion to slow down or continually start and stop. When this happens, it means the vehicle’s engine is working inefficiently. This is also known as engine hesitation and a dangerous situation can arise if this occurs in traffic.


Increased fuel consumption

A worn-out or bad spark plug causes your car to burn more fuel within a short time.

Your car fuel economy will depreciate by up to 30%. This is due to incomplete combustion. If you notice you have to fill up more often than usual it can be caused by deteriorating spark plugs. To get back to your vehicle’s optimum level of fuel consumption all you will need to do is have your spark plugs changed.


 is an authoritative car blog in Nigeria. Its objective is to get Nigerians and a wider audience to be more informed about automobiles, the automotive sector and transport infrastructure. Over the years, we have been instrumental in creating immeasurable public awareness about automobiles and their maintenance, safety and traffic laws, amongst others. ...Your mobility, our priority. NK

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