White Smoke on Startup then Disappears | Causes & Fix

Are you worried about white smoke on startup then disappears? Thick white smoke indicates an alarming engine problem that requires special attention. Generally, when the car starts, condensation of water vapors causes white exhaust smoke or steam. Mostly, the steam coming from the exhaust is harmless.

Usually, smoke appears when the engine starts and then disappears immediately. It has various types and colors and it indicates a different thing about your car health. Moreover, white smoke from exhaust is not limited to startups. This also appears from the tailpipe while accelerating or in an idle state.

Thick white smoke from exhaust indicates the repair and replacement of parts of the vehicle. In this article, I will guide you on white smoke on startup then disappears, and briefly explain the causes and how to fix them.

white smoke on startup

Causes of white smoke on startup then disappears

Gases from the exhaust pipe are the result of the combustion process. Normally, in summer, these gases are not visible. However, thin whitish vapors smoke appears from the tailpipe in the winter season and disappears after 5-10 minutes of driving. This is regular and is due to condensation.

If continuous thick smoke is coming from the exhaust and it doesn’t disappear. It indicates internal coolant leaks and other engine problems. Let us look at the reason for white smoke on startup.

  1. Coolant leak
  2. Cracked cylinder block
  3. Bad head gasket
  4. Defective fuel injector
  5. Defective ECU

1. Coolant leaks

Usually, milky appearance exhaust smoke with a sweet smell indicates internal coolant leakage. The primary purpose of the antifreeze is to absorb heat from the engine and flow it back to the radiator. Coolant entering the combustion chamber causes white smoke from exhaust. Additionally, internal antifreeze shortage causes contamination in the engine oil.

Coolant leaks are tough to diagnose and if you suspect the leakage, seek help from a mechanic. Sometimes coolant loss is due cracked cylinder head that causes antifreeze to leak into the car. Moreover, the best way to check the leakage is by checking the cylinders and spark plugs. A substandard liquid or defective cooling system causes engine overheating.

2. Cracked Cylinder Block

A cylinder block is an assembly that holds a cylinder, coolant system, and sleeves. One of the main reasons for coolant loss is a cracked cylinder head. A cracked engine block or head allows fluid to leak through the cylinder and then enter into the chamber. This leaked antifreeze causes white smoke from the tailpipe. Auto parts like head, block, and head gasket can cause severe damage to the engine. These parts require serious attention.

A cracked cylinder block is hard to diagnose, so it is best to consult a professional mechanic for the replacement.

3. Bad Head gasket

A head gasket is a cover between the engine block and heads. Generally, the purpose of the gasket is to contain combustion gasses in the cylinder. Another objective of the part is to avoid coolant and engine oil leaks. A bad gasket loses its ability to seal, which causes internal coolant loss. Leakages in the head gasket lead to poor car performance, engine wear and tear, and overheating.

4. Bad Fuel Injector

A Fuel Injector injects fuel into the car by valves that are electronically controlled. Injector equally distributes petrol or diesel into the engine to give efficiency and best combustion. However, a defective fuel injector causes the nozzle to spread uneven fuel to the combustion chamber. This excessive fuel causes an automobile to produce white or grey thick smoke.

The faulty injector is quickly figured out based on vehicle mileage. The best solution is too bad injector is a replacement.

5. Defective ECU (Electronic Control Unit)

ECU is also known as the engine control mode. This electronic control unit controls actuators on a vehicle to provide optimum performance. On the other hand, if the ECU is defective, it can cause a reduction in fuel efficiency. Fuel injector loses their sync with the piston causes an automobile to produce more smoke. You may also face poor acceleration, less brake pressure, sudden stop of your vehicle due to the faulty ECU.

Quick fix for white smoke 

white exhaust smoke

If you diagnose white smoke from the exhaust manifold, there is a defective engine block, blown head gasket, or crack in the head. First, check the coolant level if the level shows less reservoir. It indicates leakage. Sometimes the level is correct, but dripping is still present. Therefore, conduct a complete engine diagnosis and take the car to the mechanic.

Sometimes overheating is due to a cracked engine block and bad gasket. When there is a crack in the block, gasket kit, or cooling system, the pressure of the engine causes heat to build up around the hole. That causes extreme damage to the automobile. So complete replacement of engine block, head gasket, or cracked body is the recommended solution.

 1. How to fix Coolant leakage?

Coolant leakage can cause severe damage to the engine. Mostly if any liquid starts to leak from the gasket, it is hard to identify where the dripping point is. Because antifreeze leaks cause major coolant loss. Moreover, this can cause serious damage to the engine. Thus, you need to identify the dropping location and repair it immediately.

Secondly, you may take professional help if you cannot solve the coolant leakage. Besides, also repair any exhaust leak if you get.

 2. Fixing a cracked cylinder head?

Unfortunately, if you spot symptoms of a cracked cylinder head, get ready for a major repair or replacement. The authentic way to confirm a cracked engine is by removing the half engine and diagnosing the block. However, this process requires a genuine and trusted mechanic.

 3. Replacement of a bad head gasket?

If you spot symptoms like poor engine performance, overheating, white exhaust, misfiring, and coolant loss without visible leaks. It means the head gasket is broken or damaged. Gasket kit repair and replacement are expensive, and it needs a qualified mechanic.

 4. Solving a bad fuel injector issue?

Generally, blocked fuel injectors are easily repaired by cleaning the nozzle. However, sometimes lack of vehicle service causes them to be clogged entirely, which requires a replacement with the premium fuel injectors.

5. How to fix a Defective ECU?

If your ECU is not working properly, you can communicate with the ECU manufacturing companies to fix it. There are many online service providers who are repairing faulty ECUs.


1. Can bad spark plugs cause white smoke?

No, smokes from the tailpipe is not an indication of faulty spark plugs. White indicates the coolant leak, cracked head gasket or cylinder head, and fueling problem.

2. Can a bad EGR valve cause white smoke?

No, if the EGR valve is blocked. The temperature in the combustion area increase. This leads to car overheating. Generally, a bad EGR causes black smoke, not white category. What does white smoke from the tailpipe usually indicate?

Generally, the thick white smoke from exhaust is the indication of a coolant leak in the chamber. Antifreeze leak can cause overheating that can cause severe damage to the engine.

4. Will a bad injector cause white smoke?

Yes, the defective injector delivers excess fuel to the combustion chamber, causing the engine to burn extra fuel. Gray or white smoke from the exhaust is the indication of a faulty injector.


This article briefly describes the causes of White smoke on startup then disappears. Generally, white exhaust smoke in the winter season is due to the condensation process. However, sometimes thick white type with odor indicates coolant leaks and other engine issues. A professional mechanic should address maintenance and replacements problem. In my opinion, everyone doesn’t have proper tools, spare time, and complete knowledge about automotive repairs. Thus, it’s better to trust a certified mechanic.


Mr. Rubel is an Engine Mechanic. He has more than 15 years’ experience on repair and maintenance of different kinds of vehicles. He is also providing training to mechanics and works as a Senior Mechanic of a well-known organization. He is sharing his knowledge to support the car lovers to solve the vehicle issues.

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