We all know that after the engine is done using the fuel, it exhausts the gases through the tailpipe. Sometimes, the smoke coming out of the tail has some colour with it. It can be alarming. White smoke coming from exhaust on startup is also a situation that may or may not be alarming. It can happen commonly on cold winter days due to condensation. This white smoke vanishes after sometime when the vehicle heats up a bit. It is not a situation you should be alarmed about. But, if the white smoke persists even after some time, it can be due to several problems listed below:

White Smoke From Exhaust On Startup

#1 Internal Coolant Leak

The internal coolant leakage can cause white smoke coming from exhaust on startup. You can identify this problem if you smell a sweet odour. Sometimes, you can also see the low coolant reservoir level indicating a leak of the coolant.


It would be best if you got this problem fixed as soon as possible by changing the coolant. It’s the mechanic’s job, so it’s better to take the car to a professional.

#2 Cracked Cylinder Head

A cracked cylinder head or engine block is also likely to cause white smoke from the exhaust. This situation happens due to the overheating of the car. Cracked cylinder head causes the coolant to go in the combustion chamber or the cylinders, causing white smoke.


Check the cylinder heads and see if the head gasket closes appropriately. If not, get them fixed by a mechanic who knows best about them.

#3 Piston Ring or Valve Seal Leak

Bad seals or bad piston rings can also be the reason for oil leakage in the combustion chamber, where it burns and causes white smoke from the exhaust.


Get a professional’s help to solve the problem, but if you are doing it yourself, never remove the coolant cap on the running engine as it will be boiling and can cause you some serious injury. Make sure it is cooled down, then check the level of the reservoir and proceed accordingly.

#4 Bad Fuel Injector

A faulty fuel injector can deliver too much fuel to the combustion chamber. The fuel cannot burn properly and come out of the exhaust as white or grey smoke.


Replace the fuel injector or its O-ring.

#5 White Smoke Due to Transmission Fluid

A faulty car engine can absorb more fluids from the vacuum pipe, which causes the contamination of the oil, causing white smoke from the exhaust pipe. This fluid transmission problem can also cause a burning smell. It will be best if you are vigilant in checking these symptoms in your car.


You need to change the vacuum modulator valve to rectify this problem. If the level of transmission fluid is less than normal, you need to add the remaining fluid.

#6 Water Contamination of Fuel

One other cause of white smoke is the mixing of water with fuel, due to bad quality of fuel, which has water mixed already in it, or water can precipitate in the combustion chamber.


Try getting better quality fuel and reduce the air level in the engine. You can drain the water from the fuel you already have in the tank.

#7 Engine Control Unit Error

A faulty engine control unit can throw off the fuel injector’s timing, which will result in an irregular supply of fuel in the combustion chamber leading to white smoke from the exhaust.


Unplugging the battery for a few minutes solves this problem most of the time as it resets the computer. But if this doesn’t solve the problem, you may need to go to the car dealership to get it fixed as it is quite a professional task.

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