Engine troubleshooting from exhaust smoke colors |
What exhaust smoke colors means: white, blue, black

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Zero emission vehicles whether electric or not are not concerned by the color of any smoke at all !
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NOTE: The below is valid for PETROL engine only.

Comparative chart for possible car engine problems associated with smoke color.

Exhaust smoke color gives you an indication about the engine trouble you are facing depending on its color and if it occurs when engine is cold or warm. The below troubleshooting table is valid for petrol engines and covers most of the problems that could lead to a colored exhaust smoke. Do not be surprised by the blue exhaust smoke, look to the smoke coming out of your exhaust in the mirror or ask for assistance by letting someone drive your car while you drive behind it and you will be able to distinguish the white exhaust smoke which is clearly white like clouds and fog from the blueish smoke that is a bit grey with a slightly blue color showing at its edges and away from the car exhaust.

Further confirmation of the engine condition using the proper diagnostic method and tool is required to make sure of the associated engine trouble to each of the exhaust smoke color cases.
Color of Smoke
Cold Engine
Warm Engine
​Drops of Water
Normal
​Defective head gasket
​White
Normal
Defective head gasket
Blue
​
  • Fuel additive / injector cleaner added to tank (Symptoms will be reduced then vanish upon tank refilling several times)
  • Worn valve seals
  • Worn piston rings
  • Defective head gasket
  • ​Leaking turbo
​
  • Fuel additive / injector cleaner added to tank (Symptoms will be reduced then vanish upon tank refilling several times)
  • Worn valve seals
  • Worn piston rings
  • Defective head gasket
  • ​Leaking turbo
Grey / Black
  • Faulty injector (s)
  • Faulty O2 sensor
  • Faulty injector (s)
  • Faulty O2 sensor

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