Spark Plugs Burnt: Causes, Symptoms, and Solutions

Spark Plugs Burnt: Causes, Symptoms, and Solutions

Spark plugs are an essential component of a vehicle’s ignition system, providing the spark that ignites the air-fuel mixture in the combustion chambers. When something goes wrong with spark plugs, there can be many consequences, including poor engine performance and increased emissions. One common issue is when spark plugs become burnt. In this article, we’ll discuss what causes spark plugs to burn, the symptoms to look out for, and how to fix and prevent them from burning again.

What are Spark Plugs and What Do They Do

Spark plugs are small devices that create a spark when electricity passes through them. This spark is used to ignite the air-fuel mixture inside an engine’s combustion chambers. Spark plugs have metal electrodes that transfer electrical energy from the ignition coil into the combustion chamber, which ignites the fuel to generate power for your engine. A typical vehicle requires four or five working spark plugs per cylinder bank, depending on its engine design.

What Does it Mean When Spark Plugs are Burnt

Spark Plugs Burnt: Causes, Symptoms, and SolutionsWhen spark plugs become burnt, they no longer work properly because their metal electrodes have worn down due to excessive heat or electric current passing through them. This can cause them to fail, resulting in reduced engine performance, increased emissions, and a range of other issues.

Causes of Burnt Spark Plugs

There are several common causes of spark plug burnout.

  • Overheating: This is caused by an increase in the temperature of the spark plug gap or electrodes due to prolonged exposure to high temperatures and engine revs. It can be caused by various factors, such as too much fuel or air entering the combustion chamber, an incorrect spark plug heat range being used, or a build-up of carbon deposits on the electrodes due to incomplete combustion.

  • Carbon Buildup: Carbon buildup on the electrodes is another common cause of spark plug burnout. As fuel is not completely burned during combustion, it leaves behind carbon deposits which insulate the heat and prevent proper electrical current from flowing through the electrode gaps and into the combustion chamber. This can cause overheating and eventually lead to spark plug burnout if left unchecked for too long.

  • Oil Contamination: Oil contamination occurs when oil from leaking valves, gaskets, or seals enters the cylinder head and coats the spark plugs with oil. This prevents electricity from passing through the spark plug electrodes and can cause them to burn out.

  • Incorrect Spark Plug Heat Range: The heat range of a spark plug determines how much heat it can dissipate without burning out. If the wrong heat range is used, the spark plug may be unable to dissipate enough heat, overheat, and become damaged.

  • Incorrect Spark Plug Gap: Spark plugs are designed with a specific gap size which determines how large the electrical current needs to be for it to ignite fuel in the combustion chamber. If this gap is too large or small, it will result in poor performance or even burnout.

Symptoms of Burnt Spark Plugs

The most common symptoms of burnt spark plugs include:

  • Misfires: This occurs when a spark plug fails to ignite fuel in the combustion chamber, resulting in reduced power and an increase in emissions.

  • Poor Acceleration: This is caused by incomplete combustion due to misfires caused by faulty spark plugs. It can also increase emissions as unburnt fuel exits the exhaust system.

  • Reduced Fuel Economy: Poorly functioning spark plugs result in an increase of fuel being used by the engine which causes a decrease in fuel economy.

  • Rough Idling: This is caused by the engine not receiving enough energy to maintain its speed, resulting in a rough or jerky idle.

  • Engine Knocking: This occurs when fuel is not completely ignited in the combustion chamber and instead ignites after the exhaust valve has opened, causing a knocking sound.

Solutions for Burnt Spark Plugs

The most effective solution for burnt spark plugs is to replace them with new ones designed for your specific vehicle make and model. It is recommended to use original equipment manufacturer (OEM) spark plugs as these are designed specifically for your vehicle’s engine and will provide optimal performance and longevity. Along with replacing spark plugs, it is important to inspect other components of your ignition system such as ignition coils, plug wires, and distributor capsrotors to ensure they are all functioning properly. Additionally, an engine diagnosis may be required to diagnose any underlying issues that could have caused the burn spark plug or misfiring issues. It is also important to repair any damaged components, such as gaskets or seals, before replacing spark plugs, as this can help prevent future burnout issues.

How to Prevent Burnt Spark Plugs

In order to prevent spark plug burnout, it is important to take the following steps:

  • Regular Maintenance: Regular maintenance such as oil changes, air filter replacements, and spark plug replacements can help ensure your vehicle’s engine runs smoothly and efficiently.

  • Using the Correct Spark Plugs: It is essential to use spark plugs designed for your specific vehicle make and model. OEM spark plugs are recommended as they are specifically designed for your engine and provide optimal performance and longevity.

  • Spark Plugs Burnt: Causes, Symptoms, and SolutionsChecking and Replacing Spark Plugs as Needed: If you notice any of the symptoms mentioned above, it is important to check your spark plugs regularly or have them checked by a professional technician. It is also important to replace them when necessary in order to prevent further damage or misfiring issues.

  • Avoiding Overheating and Engine Damage: Make sure that all cooling systems in your vehicle, such as radiators, fans, thermostats, and hoses, are working properly in order to avoid overheating, which can cause long-term engine damage, including burnt out spark plugs.


Spark plugs are essential components of a vehicle’s ignition system and can cause many problems if they become burnt. This article has discussed the common causes and symptoms of burnt spark plugs and the solutions for fixing and preventing them from burning out again. Suppose you notice any of the symptoms mentioned above. In that case, it is important to have your spark plugs inspected and replaced when necessary in order to ensure optimal performance and fuel efficiency.

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Andy Shane

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