People are only just realising what different colours of exhaust smoke mean – and how to fix major issues

A AUTO expert has revealed what the different colors of exhaust smoke mean – and when action should be taken.

Dean Gibson explained that different shades of smoke can indicate a variety of problems or even be completely harmless.

An engine expert has explained what the different colors of exhaust smoke mean


An engine expert has explained what the different colors of exhaust smoke meanPhoto credit: Getty

Write for Auto ExpressHe said that depending on what’s going on under the hood, white, blue, gray and black smoke may be pumping out of your pipes.

Some can indicate serious problems, but most cases are easily remedied if addressed quickly.

Firstly, white smoke coming from an exhaust pipe is probably the most common occurrence.

Fortunately, it is also the least serious problem.

Most white smoke is not actually smoke at all, but rather water vapor from the air conditioning condenser or evaporating refrigerant.

However, Dean wrote, “If the white smoke coming out of the exhaust is thicker and doesn’t stop, it’s still vapor, but also a sign of a more serious problem caused by your car’s coolant leaking into the engine.”

“This could be caused by a bad head gasket (the seal between the engine block and the head that sits on top), which could be an expensive repair, but not as expensive as repairing a cracked engine block or cylinder head.”

Next, blue smoke is actually a sign that motor oil has burned in your engine.

This can be caused by a leak in the lubrication system, an overfill of oil, or simply spilling some oil into the exhaust while refilling.

It can also indicate worn valves or piston rings, which can be expensive to repair and can cause oil to run out more quickly, which can lead to damage to the engine.

Third, Dean explained the meaning of gray smoke.

He said: “Gray smoke, like blue smoke, could be a sign that excess oil has burned somewhere in the engine or that a turbocharger needs service.”

“If you drive a car with an automatic transmission, another reason for gray smoke may be that a leak in the system is leaking transmission fluid into the engine.

“This could also be an expensive repair and will definitely require the help of a repair shop.”

Finally, the meaning of black smoke depends on the type of fuel your car uses.

If it is a gasoline model, this means that it is burning too much fuel, which can usually be fixed by replacing the air filter.

However, if this doesn’t solve the problem, there may be a problem with your injectors that need to be professionally cleaned.

However, if it is a diesel engine, it could simply be due to soot deposits in the exhaust system.

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Dean advised: “To remedy this, the best course of action is to get the fuel-air mixture flowing through the car more quickly by driving it faster.”

“Find a nearby expressway or highway and quickly accelerate your diesel car to 70 miles per hour. This should dislodge the soot, which will appear as a black ball of smoke behind the car and will likely also leave soot deposits on the road.”

Alley Einstein

Alley Einstein is a USTimesPost U.S. News Reporter based in London. His focus is on U.S. politics and the environment. He has covered climate change extensively, as well as healthcare and crime. Alley Einstein joined USTimesPost in 2023 from the Daily Express and previously worked for Chemist and Druggist and the Jewish Chronicle. He is a graduate of Cambridge University. Languages: English. You can get in touch with me by emailing

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