Main Causes of White Smoke from Exhaust Pipe

A variety of situations and reasons can cause car exhaust smoke. The white smoke from the exhaust of the car can either be a simple or serious problem.

The first thing to do is to access if the white smoke looks thin like a vapour and shortly disappears or has a thicker density that smells burned and continuously flows.

A visit to a professional mechanic is highly recommended whenever any kind of smoke is emitted by your car. A better safe than sorry attitude is the best to have when it comes to your car.


White smoke from the exhaust pipe is commonly caused by:



White smoke that dissipates with a thin vapour-like appearance can simply be condensation. The exhaust emission is condensation emitted as steam. This is no cause for worry especially when this happens at startup during cold weather.

Something wrong with the EGR cooler

Condensed coolant is most likely the problem your car is having with sweet-smelling exhaust smoke. The crack inside the EGR cooler is the most common cause of this kind of white smoke emission. This particular car problem can be tough to diagnose correctly as the outside engine will not be showing any signs.

Replacing the EGR cooler is the best remedy for this. A professional mechanic can help diagnose and replace a faulty EGR cooler. Or you can take off the EGR pipes and use a coolant leak tester to look if the exhaust pipe is showing any coolant.

Something wrong with the cylinder head or head gasket

Coolant starts to leak out and mix with engine oil if the head gasket or cylinder head of the car is cracked or damaged. The engine oil becomes contaminated with the leaking coolant. This ultimately results in the sweet odour and white smoke emission in the exhaust.

A professional mechanic will have to take apart the engine to do some repairs. However, the worst-case scenario is to have the engine replaced if it is beyond repair.

Something wrong with the coolant tank/container

The white smoke can be caused by a leak in the coolant tank. Coolant tanks rarely break but they can get damaged. Repairing other nearby car parts can sometimes damage the coolant tank. When this happens, the white smoke will be emitted by the engine and not from the exhaust pipe.

The only remedy is to replace the coolant container/tank. The car will function like new when the damaged coolant tank is replaced.


Diagnosing the white smoke emitted by the exhaust


Doing some DIY diagnosing is one way to understand the cause of the white smoke coming from the exhaust pipe.


Using a pressure tester

A coolant pressure tester is probably the best way to find any internal coolant leaks. The way to do it is to fit the tester on the radiator cap. Apply some pressure inside the coolant system and let it stay for an hour. Check for any coolant leak signs inside the combustion chamber by removing the spark plugs. A cracked head gasket or cylinder head is the problem if you see the presence of coolant.

Smelling the smoke

The sweet smell of the smoke coming from the exhaust pipe means it’s a coolant problem. An odourless smoke is most likely condensation.


White smoke from the exhaust pipe could be nothing or something serious. If you want to know how to fix white smoke from exhaust, the best way is to consult with a professional mechanic ASAP.




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