Know! Have you noticed that there are different exhaust smoke colours? What do they mean?

Exhaust smoke is a way of telling you what is wrong with your car. Generally, the smoke emitted is either black, white, gray and blue. Exhaust gases are an old-school way of identifying problem symptoms, meaning that large amounts of black smoke mean that EGR is blocked and high fuel.

It is very useful to know the difference between the smoke comings from the exhaust. If you do not fix the car yourself, colour and report back to your mechanic if smoke appears. Avoiding the problem will shorten the life of the engine and lead to unnecessary repair bills.


1. White smoke

2. Black smoke

3. Blue smoke

Let us discuss the reason for each type of smoke in detail

1. White smoke:

Engine burning coolant produces thick white smoke. This can be caused by a coolant leak in the engine due to a head gasket, damaged cylinder head or a broken engine engine leak. If you notice this type of smoke, take your car to the garage as soon as possible, as leaking coolant can cause overheating that can damage your engine. Not to mention the possibility of mixing the coolant with the oil.

The causes and symptoms of white smoke vary, and are more common in gasoline cars. The most common cause of white smoke is when the car has just started. White smoke is just condensing steam that heats the car.

White smoke from a petrol / gasoline car

As mentioned white smoke is can be common while starting your vehicle, but if it continues when it is hot, you have a problem. Check the following for the cause of white smoke in petrol cars:

  • Head gasket failure
  • Turbo problems
  • Overheating engine
  • Ruptured engine block

White smoke from a diesel car

Sadly, the white smoke emitted from a diesel car running at its optimum temperature is bad news in most cases. Check the following for white smoke in diesel cars:

  • Worn or leak injector
  • Poor quality diesel
  • Low cylinder compression

Usually caused by other components such as malfunction of the piston rings.

2. Black smoke:

Black smoke emitted from a car is more common in diesel cars. Unlike when the car is cold, white smoke should never come out of the diesel car exhaust. Most of the older diesel cars emit black smoke under heavy acceleration, but newer diesel cars do not emit any black smoke. This puts very little miles per gallon and extra pressure on the engine parts.

Compared to diesel engines, petrol engines rarely produce black smoke from the exhaust. In almost all cases, the black smoke emitted from the petrol car is due to the fuel ratio to the air.

The black smoke emitted from a diesel car is caused by the proper combustion of the fuel. This problem is due to insufficient airflow or poor quality diesel generated in carbon deposits. The following are the causes of black spots from diesel car exhaust:

  • Clogged air filter
  • Damaged fuel injector
  • Faulty MAF (Mass Airflow Sensor) Sensor
  • Bad EGR valve
  • Damaged piston rings
  • Engine deposit
  • Low quality diesel fuel.
  • Defective turbocharger and poor air to fuel ratio

3. Blue smoke:

Blue smoke indicating that the car is burning engine oil. When the piston rings malfunction and the oil leaks into the combustion chamber it ignites with fuel.

For a turbocharged car, the smoke indicates that the blower needs to be replaced. Burning oil starts mostly because it destroys the spark of the car.