What Does a White Tip Spark Plug Mean?

Spark plugs are an essential ignition system component that ensures your vehicle starts. However, they can get fouled due to age or other faulty components. Meanwhile, faulty spark plugs appear in different colors. If your spark plug tip is white, it means that car engine is running too hot which burns out plugs.

Sometimes a fouled spark plug may have black soot on the tip, and other times white, oily, etc. Reading Spark Plugs or understanding these colors is easy to spot why your plugs are failing and reveal your engine’s condition. This brings us to ask what does a white tip spark plug mean?

what does a white tip spark plug mean

What does a white tip spark plug mean?

A white tip spark plug means your spark plugs are burned due to running too hot. However, there is something to keep in mind. If the white deposits are relatively weak, there is nothing to worry about.

It is very common for spark plugs to form carbon deposits since they operate under high temperatures. Iron oxide and fuel impurities can cause this whitish color when oxygen meets with the plug’s steel body.

However, if thick white deposits are on the spark plug tip, you might have a more severe problem. Now, if these thick white deposits form due to spark plugs running too hot, why do spark plugs get too hot? It can be due to using low quality fuel, or problems in the ignition system.

What causes white spark plug

Since the white tip spark plug indicates spark plugs running too hot, let’s see why they are running too hot.

Uneven air-fuel mixture

For complete combustion to occur, the combustion chamber needs the air-fuel mixture in a particular proportion. Now, certain components, like the mass airflow sensors, injectors, carburetors, etc., are responsible for ensuring that this air-fuel mixture is in the correct ratio.

When they get faulty, it can result in your engine running on lean air fuel, resulting in the car not reaching its normal operating level or the engine misfires. Ultimately resulting in black plug or white deposits forming on the tip of your spark plugs.

Engine overheating

An overheating engine exposes the spark plugs to operate under temperatures higher than usual. The excess heat invariably forms white deposits on the spark plug tip. An overheating engine may indicate your cooling system is not functioning well.

Low-quality fuel

Poor quality fuel causes your engine to work harder than usual—invariably producing excess heat. White residues will form on its tip with your spark plugs exposed to such heat.

Incorrect ignition timing

The spark plugs are supposed to ignite the air-fuel mixture in the combustion chamber at a particular time. If the ignition timing over stretches, the air-fuel mixture can shoot too early, leading to engine explosion and heat. With your spark plug exposed to such heat, white residues will form on the plug’s tip.

Worn, loose or incorrect spark plugs

When spark plugs are bad or loose, they find it difficult to ignite your air-fuel mixture in the combustion chamber. This ignition delay often causes detonation of the mixture, resulting in engine explosion and heat. In addition, the plugs exposed to such temperature often lead to white tip spark plug.

Again, every vehicle uses specific spark plugs that can withstand engine heat. If you use an incorrect spark plug, it may not be able to withstand your engine’s heat range. Hence the excess heat leads to white residues on the plug’s tip. Or it could be that you fitted your vehicle with spark plugs whose heat range is too high.

Can bad spark plug cause a lean condition?

NGK Iridium Spark Plugs naturally will not cause a lean condition. They have to create ignition to burn the air-fuel mixture. However, they can trick the oxygen sensor to create a lean condition when they go worn. Here is what happens.

When spark plugs go bad, they fail to ignite the air-fuel mixture, resulting in incomplete combustion.  Unburnt fuel, due to incomplete combustion, invariably gets dumped in your exhaust.

With unburnt fuel in the exhaust, the oxygen sensors may think that the combustion chamber is getting too much fuel from the fuel injectors.  When it relates this information to the ECU, the ECU reduces the amount of fuel entering the combustion chamber and pumps more air instead.

What color should the tip of a spark plug be?

The tip should be grayish tan or brown for a normal spark plug that has been running for several thousand miles. However, when something goes wrong, this color may change. Generally, what color it changes depends on what component is causing it. This is why it is essential to understand the spark plug color chart, as it would tell you which component needs fixing.

For example, dry black soot on the electrodes and insulator tip indicates that your plugs are fouled by carbon deposit. Often resulting from regularly driving at low acceleration, dirty air filters, long idle, or running rich air-fuel mixture.

A black oily deposit on the spark plug tip may mean oil leaks into the cylinder and gets past worn pistons and valve guides. Therefore, a practical way to identify potential engine problems is to understand your spark plugs by studying the spark plug chart.

White Deposit on Spark Plug YouTube

How to check spark plugs are white on the tips?

Checking the white spark plug tip is an important aspect of vehicle maintenance, as these deposits can indicate various engine issues. Here is a step-by-step guide on how to check white tipped spark plugs:

  1. Safety first: Ensure the engine is cool before you start. Wear safety gloves and eye protection.
  2. Locate the spark plugs: Consult your vehicle’s manual to find the location of the spark plugs. They are typically situated on the top or side of the engine and connected by thick rubbery wires.
  3. Remove the spark plug wires: Gently twist and pull the spark plug wires to remove them. It’s important to do this one at a time to avoid mixing up the wires, which could lead to engine misfiring.
  4. Remove the spark plugs: Use a spark plug socket and ratchet to unscrew each spark plug from the engine. Turn counterclockwise to loosen.
  5. Inspect the spark plugs: Once removed, inspect the spark plugs for any white deposits. These deposits can appear as ashy, powdery residues on the electrode and insulator.
  6. Understanding white deposits: Spark plug white residue can indicate a lean fuel mixture, overheating, or oil leaks. They may also suggest the use of low-quality fuel or additives.
  7. Check for other signs of wear: Besides white deposits, look for other signs of wear, such as electrode erosion, cracks in the insulator, or any burnt marks.
  8. Deciding on action: If the spark plugs have white deposits, it might be necessary to replace them. However, it’s also important to address the underlying cause of the deposits, such as checking the fuel system or cooling system.
  9. Replace spark plugs: If the spark plugs are in good condition, screw them back into the engine and reattach the wires. If they need replacing, ensure you use the correct type for your vehicle.
  10. Seek professional advice: If you are not confident enough in interpreting the condition of your spark plugs or if you find severe deposits, it is wise to consult a professional mechanic.
white spark plug tip

Regular checking and maintenance of spark plugs are crucial for the smooth operation of your engine or avoid any trouble.

How to fix white spark plug tip

Generally, a spark plug tip gets whitened when it is running extremely hot. So to fix a white tipped spark plug, you first need to know which component makes your spark plugs hot.

While we’ve stated why plugs run hot, a proper analysis or inspection will point you to the real culprit.  You can fix a spark plug white tip by doing the following.

  • Change faulty injectors and carburetors. If the carburetors are not correctly adjusted, adjust them.
  • Drain out bad fuel and fill your gas tank with a premium fuel tank with the correct octane level.
  • Change worn-out spark plugs.
  • Use the correct spark plugs recommended by your vehicle manufacturer.
  • Ensure all components of your cooling system are working well.
  • Replace with a cold range spark plug if your spark plug heat range is too high.
  • Lastly, clean the white residues from the spark plug after fixing whatever is causing it. However, cleaning is only possible if the white residues are few.  If  you have a thick build-up, you would need to replace the plugs.

Cleaning white residues from spark plugs

fouled spark plug cleaning

Tools needed

  • Sandpaper
  • Socket wrench or screwdriver head
  • Cleaning agent (solvent)

Method 1

Locate the spark plugs. Then remove the high voltage wiring or the individual coils screwed into place with a screwdriver head or socket wrench (depending on your model). Next, fold a sandpaper in half and remove the white residue between the electrodes carefully. This method is not recommended for iridium plugs.

Method 2

Use the solvent to clean the spark plugs and the electrodes. Alternatively, you can put the plugs in a bowl, add the cleaning agent and let it sit there for a while. Afterward, rinse with a solvent to remove the remaining residues. If some residues are still left, clean with a towel. Return them to your car when they are dried.


For those wondering what does a white tip spark plug mean? It means your spark plugs are burnt due to running hot. This could be due to faulty injectors/carburetors causing a lean fuel. A bad or incorrect spark plug and low-quality fuel could also run out your plugs.

The only way to fix a white tip spark plug is to repair those components responsible for it. Failure to fix these components will cause your engine to suffer damage since these components also work with other components.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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