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What Does A Bad Spark Plug Look Like

What Does A Bad Spark Plug Look Like: Traces & Fix

All cars, motorcycles, and trucks use spark plugs for ignition. This unit will create sparks when fuel is injected. They then ignite and generate energy to keep your car running.

Spark plugs are subjected to a tremendous amount of heat to keep the car engine running correctly. Therefore, this part is often straightforward to corrode and fail. If you start your vehicle one day, but the machines don’t work, as usual, the culprit could be the spark plug.

So what does a bad spark plug look like? Usually, this part, when damaged, will show signs of black or rust. Let’s learn how to recognize a spark plugin that needs repair and fix it to help your car work better.

About Bad Spark Plugs

About Bad Spark Plugs

A spark plug is quite an essential part of the car engine. Therefore, as soon as this part has a problem, your car will not operate normally.

There are many signs that a spark plug needs repair. You can immediately tell when the car feels sluggish when accelerating. Because when this part is having a problem, the ignition ring system will also not work correctly. As a result, your vehicle will not receive enough fuel to start.

Not only that, you will also recognize when the engine light is on. This light system will alert you when something inside is having problems. Please quickly check the spark plug as it may need repair.

In addition, if you have to refuel more than usual regularly, the problem is in the spark plug. When this part cannot ignite correctly, the gasoline or oil fed into the engine is not used to its total capacity. If not repaired in time, it will cost you a lot of money to replace new parts.

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What Does A Bad Spark Plug Look Like?

What Does A Bad Spark Plug Look Like

Bad spark plugs come in many different shapes. You can refer to some external signs that this part needs repair:

Carbon deposits

When the spark plug is not working correctly, it will deposit carbon deposits on the end and middle of the torsion. When spark plugs accumulate deposits, they will show a black and dry mark on the conductive terminals. You can disassemble this part for inspection.

The cause of carbon deposits is that your car is using the wrong type of spark plug. If you usually drive at low speed, this will happen.

In addition, this part of the residue can also be caused by the filter system being too dirty. The dirt has entered the vehicle fuel, but the filter cannot control it. As a result, carbon deposits have formed and adhered to the spark plug.

Spark plug sticks to oil for a long time

Long-term oil retention is common when a spark plug encounters an error. This part will deposit black deposits, and the electrode tip has oil.

The phenomenon of oil sticking usually occurs when the oil inside the engine is leaking. You can test cylinders, pistons, or other parts that use oil. If the spark plug gets too much fat, it won’t operate at its total capacity. Ignition work will also not work correctly.


In addition to sticking to oil for a long time, spark plug soaking in water is also a common phenomenon. You can notice after inspecting this part that the spark plug is collecting a few drops of water and gradually changing color.

Spark plug ingress is inevitable. Because your vehicle will often have to operate in the rain, water droplets will seep into the engine and damage the spark plug over time. When soaked in water for too long, this part will rust, and it won’t be easy to continue using.

Electrode wear

External factors do not cause electrode wear. This phenomenon is simply because the spark plug has been active long enough and needs replacing.

You can tell when this part is seriously corroded. The spirals are all turning black, and the terminals are rusting. When they are no longer usable, you need to replace spark plugs immediately because they can no longer work properly.

On fire

As we said above, spark plugs are subject to a large amount of heat because of their role in igniting fuel. Therefore, when this part does not work correctly, it will lead to a fire. A white residue appears on the top of the electrode. You can feel the heat when you disassemble the spark plug for testing.

The cause of spark plug fires may be that this part is not installed properly. The spark plug inside the engine is too loose, leading to the ignition system not working correctly. Not only that, the operation timing of these two parts is not accurate.

In addition, spark plug fire can also be caused by the engine running too hot. When your car operates at too much efficiency, the spark plug needs to continuously burn fuel to supply the machine and lead to overload.

How To Fix A Bad Spark Plug For A Car

How To Fix A Bad Spark Plug For A Car
After you have identified the signs of the wrong spark plug types, you need to take steps to improve this part:


If your spark plug is collecting carbon or oil deposits, you can easily clean those stains. You can follow these steps:

  • Prepare a brush and clean water.
  • Rub all the dirt on the electrode tip and wash it with water.
  • After cleaning, wait for the spark plug to dry.
  • Install the engine.
  • You can do this job at home because the cleaning steps are straightforward.

Replace the newer one

As for broken spark plugs that cannot generate sparks, you need to replace them immediately. You can find this part on websites or shops that specialize in car accessories.

There is a small note that you must buy the correct spark plug suitable for your vehicle. Would you please check the old model and look for the identical one to ensure the car can work properly after installation?

If you cannot do the replacement yourself at home, take your vehicle to a local auto repair center. Here, experts with many years of experience in installation and repair will help you do this job.


The Spark plug is an essential part of keeping your vehicle running at its total capacity. Therefore, regularly check the engines for timely repair and replacement. Hopefully, the above article has helped you recognize what a bad spark plug looks like and how to fix it effectively.

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