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The Meaning of Exhaust Gas Colours

Model: (Various brands) Various
Part: Checks and maintenance

Video tutorial

Let’s see how to perform a preliminary visual diagnosis of problems with your car by examining the colour of the smoke coming from the exhaust. Thick, persistent white smoke indicates a problem with the coolant entering the combustion chambers.

It signals a possible damaged head gasket. Blue or bluish smoke indicates engine oil burning in the combustion process, suggesting wear on the seals or piston rings.

Grey smoke indicates excess oil or a transmission fluid leak burning. Black smoke indicates a fuel/air mixture that is too rich (too much fuel and not enough air), common in diesel engines or with injection problems.


Posted on 16 April 2026 by ScegliAuto


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by ScegliAuto

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