White Smoke from Exhaust: Causes and Fixes

It’s not unusual for mechanics to deal with cars emitting different types of smoke from the exhaust. However, what many car owners fail to understand is that the severity of the issue depends on the type of smoke. For instance, white smoke from the exhaust is popular, and it’s not only produced when the car is on the move. Sometimes you find the smoke coming out even when the car is idle or when it’s cold outside.

All in all, no matter how you notice the white smoke, it is essential to take care of the problem before it gets worse. Therefore, take a trip to your mechanic in order to avoid any further damage to your engine or exhaust system. Although it’s good to leave the job to the professionals, we believe it is also wise to have some general information on what causes the white smoke.

That’s why in today’s article we are going to share with you what white smoke means, its main causes, as well as answer some other questions related to this issue.

What Does White Smoke Mean?

It is basically the result of steam that’s found itself inside your car’s exhaust system. However, you can determine whether it’s a big issue or not depending on how thin or thick the smoke actually is. For instance, if it is thin like vapor and disappears shortly after starting the car, then you have nothing to worry about.

The reason behind this is that most cars emit white smoke on startup then disappear when the engine and exhaust reach their natural operating temperature. In addition, it is good to note that the white smoke can also be emitted as a light shade of blue, which is an indication of oil entering the cylinders and getting burnt.

On the other hand, if the smoke is thick and is continuously present, you should be concerned. The thick white smoke mostly comes from a fault in the coolant system that usually leads to a major problem like a blown gasket, cracked engine block, engine overheating, or even a damaged cylinder head.

Firstly, when we look at the head gasket, this part is a thin metal sheet found between the Cylinder head and block. In fact, it sandwiches the top and bottom parts of most engines. Its main function is to form a seal between the two parts.  Additionally, it also helps to prevent coolant leaks from the cover surrounding the engine.

So, what brings about the coolant leaking when the gasket is affected?

One of the reasons is the gasket wearing out or just having a tear. When this happens, the coolant is no longer contained within the cooling channels of the engine. If it leaks out of the channels, the coolant flows into the cylinder where it gets burnt and eventually comes out of the exhaust in the form of white smoke. This issue will not stop until the head gasket gets replaced.

Remember, it is vital that you stop driving the car as soon as this happens since a small leak can worsen and become a flood that may cause serious internal engine damage which may not be easily repairable. What’s more, if the engine runs out of coolant, it will cause it to overheat which may lead to further damage not only to the engine component but to other parts of the car too. This is not good news at all for you since you might find yourself spending a lot of money replacing the damaged parts.

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 What are the Main Causes of White Smoke from the Exhaust?

As you have learned from the above question, there are various ways your car emits white smoke from exhaust pipes. However, we are going to look at the main causes of this issue.

01. Condensation

One of the main causes of white smoke is condensation. This usually happens when the weather is colder or when your car has been idling for some hours. The other factor that might contribute to the white smoke is when you go from a warm area to a cold one. So, what is condensation? Condensation happens when the warm exhaust gases meet cold outside air, causing steam. However, if this happens, you shouldn’t worry, since it usually goes away after a few minutes of driving.

02. Leaking Coolant

Another cause of white smoke is leaking coolant. The leakage will be noticeable when the smoke is visible while driving the car. Furthermore, there will also be a sweet smell coming out of the exhaust pipe. Don’t let this fool you as the sweet smell is a cause for concern.

There are several reasons why the coolant might be leaking; one of them could be from a cracked engine block or cylinder head. No matter how small the crack may be, there is a possibility of the coolant leaking into and contaminating the oil. When this happens, it will create thick, milk-like smoke.

03. Broken Fuel Injection Pump

It’s common to experience white smoke from exhaust diesel when the injection pump timing isn’t working. What does this mean? Simply put, the fuel injector is usually responsible for adding fuel to the combustion chamber. Therefore, if your car has a defective fuel injector, white smoke will form due to the improper amount of fuel added. It’s not advisable to check the injection or try to change it on your own. This is a job best left up to the pros.

04. Oil Leak

Oil is an important factor when it comes to your car operating properly. However, it can leak out of the valve seals or piston rings and flow into the internal combustion chamber, thus mixing with the fuel. If this happens, it will cause white smoke or even blue smoke to appear from the exhaust pipe. It’s recommended to fix the oil leak as soon as possible in order to avoid any further issues or damage.

05. Damaged/Cracked Coolant Reservoir Tank

Although a damaged or cracked coolant reservoir tank is less common than a leaking coolant, it does happen from time to time. This could happen if a mechanic accidentally damages the tank while fixing another problem or even if the car owner decides to poke around the car.

Regardless of how it happens, white smoke will be present when driving the car. Don’t let it get worse, just replace the reservoir tank.

06. Engine Control Unit Error

Finally, a faulty or glitchy engine control unit causes white smoke to come from the exhaust. What the engine control unit does is throws off the timing of the injectors, therefore, creating an error even though the injector itself is not damaged. The good news is that all you need is to fix or reprogram the control unit and restore the correct timing of the fuel injection pump.

One way to fix this issue is by simply unplugging your car’s battery for a few minutes to reset the computer. If that doesn’t work, visit your mechanic.

How Do You Fix White Smoke from Exhaust?

There are various parts of the car you should check to determine why your exhaust gives off white smoke. One of them is the head gasket while the other one is the coolant. There are several steps you need to take to be able to fix the white smoke issue.

Intake Manifold Gasket

Check Out The Intake Manifold Gasket

The first thing you should check out when you see white smoke coming out of your exhaust should be the intake manifold gasket. As you know, this gasket seals the manifold not only transporting coolant to the engine but also oxygen. If the intake gasket gets damaged, the engine gets overheats due to the leakage of coolant, air, and gas. Keep in mind that the gasket is mostly made of rubber or plastic. Therefore it is prone to damage caused by extreme heat. Although it can get cracked or damaged, it can easily be repaired if detected early.

Further, Examine the Head Gasket

After checking the intake gasket, you should move on to the head gasket. This gasket is designed to seal the head to the block. Its main function is to so prevent the coolant from going where it is not supposed to.  If the head gasket has an issue, it needs to be fixed immediately.

Look Closely for Cracks in the Cylinder Head

As you know, the cylinder head is connected to the engine block and head gasket. Due to the fact that it’s made of aluminum, it’s prone to warping or breaking if your car overheats, thus releasing the white smoke. Therefore, it is necessary to carefully check it and if you spot a crack, change it right away.

Coolant Level

Inspect the Coolant Level

The first step is to open the hood of your car and inspect the coolant. However, don’t forget that the engine should be cool before you remove the radiator cap or reservoir cap. If the engine is hot, give it 30 minutes or so to cool down before you attempt to check the coolant.s.

Open the Coolant Reservoir

After you’re sure the engine has cooled off, open the coolant reservoir and see if the coolant level is the cause of the white smoke. One way to check the coolant is to look into the coolant chamber or put a stick into its reservoir and check how much coolant there is. Keep in mind that the stick will give you the exact amount of coolant left in your car, which is more accurate than just looking inside the coolant chamber (what else are you going to look at it with?).

Check Other Areas of the Engine

If the amount of coolant is adequate, it’s time to move to other areas of the engine, such as the cylinder head, head gasket, and even the engine block itself. Check if these parts have any cracks or damage that may lead to the coolant mixing with the oil or fuel.  If it’s possible, you should also perform a cooling system pressure check to try to determine which part is actually causing the leak.

The Difference Between Diesel Engine and Petrol Engine White Smoke from Exhaust

The difference between a petrol and diesel car releasing white smoke is brought about by different problems.  That’s why it is essential to know the main causes.

Diesel Engine

white smoke from diesel engine on startup
white smoke from a diesel engine on startup

When you encounter white smoke in your diesel-powered car, it means the fuel is not burning correctly due to a lack of heat in the combustion chamber. The un-burnt diesel does not only cause white smoke but also contains certain toxins that will likely sting your eyes.

There are several causes of white smoke in a diesel-powered car. These include:

  • Water is mixed with the diesel, which is mostly in the cylinder head or block or is caused by a cracked head gasket.
  • Damaged injectors
  • Low cylinder compression
  • Broken injection timing
  • Cracked or damaged rings or cylinder liners
  • Damaged fuel lines
  • Low fuel pressure to the fuel pump
  • Incorrect or broken fuel pump timing
  • Broken crankshaft keyway

Most cars experience a coolant leak when a broken head gasket or cracked cylinder head, or damaged engine block is at fault.

Petrol Engine

White Smoke petrol engine
The white Smoke petrol engine

Just like diesel-powered cars, the petrol engine has various causes that result in white exhaust smoke. Before we look at the causes, it is good to note that white smoke in a petrol engine is caused by water entering the cylinder and mixing with the fuel.

Basically, the white smoke is steam and is kept away from the cylinder by the head gaskets. Inside the cylinder, a mixture of fuel and air mix together, compresses and finally ignites to enable the car’s engine to function properly. Therefore, any amount of water that enters this area will produce steam that is presented as white smoke in the exhaust pipe of your car.

If white smoke is present, all you have to do is check for the proper amount of water inside the radiator and the overflow tank. Don’t forget also to check if the engine oil is also contaminated.

So, which are the other common causes of white smoke?

White Smoke from Exhaust Diagnosis YouTube Video:

White Smoke from Exhaust FAQs

Question: Can I Drive My Car with White Smoke?

Ans: It’s really not a good idea to drive your car while there is white smoke coming out of the exhaust. Why is that you ask? First of all, it means your car may have engine problems such as an engine oil leak that may drip from the car’s gasket. This might cause serious damage to the car’s engine or even start a fire. Therefore, ensure you get your car checked out immediately if you notice any white smoke coming out of the exhaust.

Question: What Causes White Smoke From Exhaust When Accelerating?

Ans: Simply put, there are two ways that cause white smoke from the exhaust when accelerating. One of them is because of the transmission fluid and the other is burning coolant. When we look at the transmission fluid issue, white smoke is present when the engine sucks fluid through its vacuum hoses.

Additionally, the smoke is also known to leave behind an oily smell. Aside from that, a vehicle burns coolant when the car’s cylinder head or gasket is cracked and starts leaking. This usually is bad news as the leak gets mixed with the engine oil therefore it contaminates it which results in white smoke. Keep in mind that the white smoke will also have a lightly sweet smell to it.

Question: What Causes White Smoke From Exhaust When Idle?

Ans: The most common factor we know of that leads to white smoke when the car is idling, is oil getting inside the combustion chamber (not necessary, it is implied). This simply means that the presence of oil in the combustion chamber goes into your car’s exhaust system and creates white smoke. It is quite easy to know the presence of oil as it’s different from gasoline in terms of color and smell. But hey, don’t forget that this problem should be dealt with as quickly as possible to avoid any further damage, such as the spark plug.

Question: What Causes White Smoke From Exhaust to Smell Like Gas?

Ans: Mostly what causes white smoke from exhaust smells like gas is water vapor. This happens when the water finds itself in the combustion chamber. When this happens, you see water dripping from the exhaust pipes. If you do find water in the fuel, you should replace the fuel immediately before driving the car (implied). Although most owners think it is normal, you should take your car to the mechanic and have it fixed immediately.

Question: What Causes White Smoke from Exhaust When it is Cold?

Ans: It’s quite common to see white smoke from the exhaust when cold. You should be concerned if you notice continuous smoke while driving, especially if you are having a diesel car. That’s because the smoke may be present due to leakage of coolant going through the engine. It could also ve be from incorrect fuel injector timing. Ideally, it is good to pay more attention to the white smoke your car releases when it’s cold outside in order to avoid any further damage.

Question: How Much White Smoke from Exhaust is Normal?

Ans: One factor that should not worry you is when you see the thin white smoke from the exhaust. That’s because the smoke is probably a result of steam that forms in the exhaust system. Since the white smoke is most likely vapor, it usually disappears quickly. This kind of thin smoke is seen mostly when it’s cold outside or when you first start the car. However, if you notice the smoke getting thicker and doesn’t go away, we recommend you visit your mechanic.


I don’t think there is anything else we can add concerning white smoke. As you have learned, just like the black smoke, as well as other types of smoke coming out of your exhaust, white smoke is not something to be ignored. Not only does the smoke cause problems (implied), but it can also affect other cars that are driving behind you.

It’s very crucial for you to notice early on if there is white smoke coming out of your car’s tailpipes. Meanwhile, if you find any trace of smoke, you should make sure it is not just steam or caused by the outside temperature. So, tell us to have you noticed any white smoke coming out of your exhaust lately?

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Hi there, I am R. Hasan Tito, a mechanic, and owner of this website. My friend and I created this website to share our knowledge, expertise, and experience with our fellow mechanics' community and car users. I am a specialist and certified automotive mechanic (Both Heavy Commercial and Private Cars). I worked as a Mechanic and Mechanic Supervisor for over fifteen years at Global Rebound Automotive companies - Toyota, TATA, BMW, Nissan, TVs, and Others. Now, I enjoy my new role of leading a team of automotive experts (in their respective fields) and publish new content on a regular basis on my website and social media.

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