Updated at: 15-07-2022 - By: Lucas

Spark plugs play a critical part in ensuring that the engine is running properly. When they wear out, they will need to be replaced. In addition to their wear and tear, spark plugs can be used to detect other issues, such as a potential engine malfunction, based on their color.

Deposition on the surface of spark plugs is common since they are exposed to high temperatures. When oxygen is supplied to a steel body, iron oxide and fuel impurities create these natural colors. In the event of a malfunction, these colors will change.

If you see white build ups on the spark plugs, this might be a problem in the power supply or ignition system, or the wrong fuel is being used in the vehicle.

You shouldn’t be alarmed if you notice extremely weak white deposits on your spark plugs and your vehicle is equipped with an LPG system, even if the deposits are glossy or thick.

Unlike gasoline and diesel, which both contain additives, regular gas does not. Its combustion temperature is slightly higher, and a small white carbon deposit will form on the body.

As a result, if the engine works smoothly, there is no excessive fuel consumption or antifreeze leakage, and the ECU does not have any problems, there is no need to worry about the situation.

Why do white build-ups form on the spark plugs?

It is common for white deposits to develop up on spark plugs as a result of a poor ignition process caused by a low fuel air ratio or no ignition at all. Being exposed to high temperatures, the dark carbon deposits burn out, while the more persistent light colored ones remain.

Causes and solutions of white spark plugs

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1. Unstable air-fuel mixture

There is a risk that the engine won’t be operating at its best in this situation. Your engine’s camshaft position sensor, crankshaft sensor, and mass air flow (MAP) sensor should all be inspected.

2. Spark plugs are worn.

White deposits on the spark plugs can form if these components fail or if you use low-quality fuel. If the engine’s cycle is disrupted, you’ll notice a considerable decrease in performance.

You can attempt to clean the spark plugs by using high-quality fuel and additional additives, but replacing the spark plugs is the preferred option.

3. The car is using low-quality fuel.

White deposits on your spark plugs are a sure sign that you’re using fuel laced with substandard additives or counterfeit fuel. Consequently, the engine will run poorly and its components will wear out more quickly, most notably the oxygen sensor and the catalytic converter, which will fail considerably more quickly.

To fix this issue, you could try refueling with high-quality fuel and replacing your spark plugs.

Glossy white deposits on spark plugs

Deposits on the spark plugs might take on a variety of shapes depending on the issues that may arise. The ground electrode of a spark plug is frequently coated with a shiny white coating. Engine performance will suffer as a result, and it may be an indication of more serious issues.

The shiny deposits on the spark plugs can be attributed to:

Cylinders and valves will overheat, and pistons and spark plugs will wear out more quickly as a result. The engine oil’s protective characteristics will deteriorate faster as a result. There is a risk of a lean mixture, faulty ignition and the appearance of detonation when the engine’s power is reduced (engine knocks).

It is important to inspect the intake system, including the pipes, manifold gaskets, and nozzle seals. Adjust the ignition system, and if necessary, inspect the timing belt. Remove the low-quality fuel and replace it with high-quality fuel with the correct octane number.

Finally, replace all of the spark plugs with new ones in accordance with the manufacturer’s specifications.

Thick, rough white soot deposits on the spark plugs

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There could be additional things in the combustion chamber such as coolant or oil if you detect this type of deposit. Typically, valve seals and cylinder head gaskets will need to be replaced to fix this issue, so you’ll need to check the engine as soon as feasible.

Spark plug soot buildups, like glossy buildups, are caused by a lack of correct mixture formation and ignition timing as well as by additives and contaminants found in the fuel.

A thick layer of white soot coats the spark plugs for no apparent reason.

The most prevalent causes of the gritty white soot on spark plugs, as described above, are as follows:

Because there are so many possible causes for this, finding a solution might be difficult. Visit a licensed facility and have them do every test they can think of to determine the root of the problem.

How to check spark plugs for white deposits

To avoid significant difficulties, it is important to know what is causing black or white deposits on the spark plugs. The spark plugs must be checked on a regular basis for proper maintenance. You’ll need these things to get started:

It’s a simple process that shouldn’t take long at all. All that differs between models is that in some, the high voltage wiring must be removed from the plugs first, and in others, the individual coils that are screwed into place require a socket wrench or screwdriver head.

Keep track of the spark plug wires by labeling or detangling each one individually.

How to remove white deposits from spark plugs

Remember to clean the spark plugs after you have taken care of the condition that led to the soot. Spark plugs can be cleaned and reused if there are just a few deposits, but if soot or buildups are thick and numerous, they will need to be replaced.

To remove white deposits from spark plugs, there are two ways to do so: the first is to use the following:

Fold the fine sandpaper in half and carefully remove the plaque from the gap between the electrodes. Take care not to damage the spark plugs in the process. Do not use this method to clean iridium spark plugs.

Chemically cleaning the spark plugs is another option you should consider. To avoid harming the electrodes, this is the ideal method of cleaning them. Spark plugs with a higher price tag can benefit greatly from this. You’ll need this if you want to

A solvent can be used to clean the spark plugs first, then the working section (the electrode) can be put in a cleaning agent. It is possible to put the plugs in a bowl of cleaning product and then add the product to the bowl and mix. Leave them there for a while, and then rinse them with solvent to remove the remaining deposits.

The spark plugs can now be dried and put in the engine after removing the white buildups. Non-flammable liquids can be heated to speed up chemical reactions, but they should not be brought to a rolling boil. Use gloves, too, for your own protection.

This procedure may not remove all of the soot, but it does make it simpler for a towel to remove it.


If you notice white soot deposits on your spark plugs, there are numerous reasons for this. The engine will suffer in the long term if the cause of these buildups is not found and remedied. I hope the foregoing explanations have given you a better understanding of how these buildups occur and how to deal with them.