Smoke Signals: 4 Vehicle Exhaust Colors and What They Tell You

You know what the different colors of the traffic lights mean: green means ‘go,’ red means ‘stop,’ and yellow means, ‘slow down (not speed up).’ You expect the traffic lights to change color, but what about your car’s exhaust? If you’ve owned your car for some time, chances are you’ve seen your smoke go black, blue, grey and/or white at some point. Though it may not be immediately obvious, these colors tell you that there’s something wrong with your car, and the colors themselves help you identify what they are.

Black smoke

If the smoke coming from your pipes is black, this usually means your engine is not getting enough outside air, so it ends up burning too much fuel. Check your air filter to see if it’s clogged, and clean or replace it as you see fit. If your air filter is fine but your tailpipe is still emitting black smoke, the problem could be in your fuel injectors, manifold, or other areas. Bring your car to your mechanic to see why it’s burning more fuel than usual.

Blue smoke

When the smoke is blue, that tells you there’s an oil leak inside the engine and the engine is burning oil. Issues that lead to an oil leak within the engine includes damaged valve seals, worn cylinder walls, or broken piston rings. If blue smoke appears during acceleration, the problem may be in the piston rings. If at deceleration, the issue likely lies in the cylinder head. Note when you see the blue smoke and relay the information to your service technician once you bring your car in for diagnosis.

Grey smoke

Grey smoke suggests that your engine could be burning transmission fluid. This issue is often accompanied by a sweet yet burning smell. Other causes of grey smoke are faulty turbocharger and the engine using too much oil. Needless to say, when your pipe belches out grey plumes, it’s time to take your car to the shop.

White smoke

White smoke indicates coolant leak, so at best, the problem likely lies in your engine’s head gasket. At worst, you may already have a cracked cylinder head or engine block in your hands. If your engine is leaking coolant, overheating may soon follow, so it goes without saying that this is not a problem you should dilly-dally to get fixed.