Your car is smoking! Sometimes that’s not a compliment.
Well, of course, the tailpipe is meant to expel exhaust gases this way But, it may not be the right kind of gas always. With the manufacturers moving towards more efficient internal combustion engines using advanced converters, modern cars leave anything visible behind. But there are times when you take a glance on your rearview mirror and you find a trail of smoke chasing your car. If your car exhaust spits funny, you need to check out this blog post.

To put is simple and straight, smokey tailpipes are a sign that your vehicle isn’t healthy and needs repair. Realising that smoke is coming out of your car is always a nerve-wracking and frustrating thing. Something is wrong if the smoke is coming out of the hood or the tailpipe. Figuring out the problem isn’t always easy.

How a Car Exhaust System works

Starting with the burning of fuel in each cylinder, creating exhaust gases. These gases then make their way out of the cylinder, which then flow through the exhaust manifold and into the exhaust pipes. In between, these gases travel through a Catalytic Converter where the harmful, poisonous gases are sifted down to the accepted level of emission. This procedure also reduces the gases into water. And finally, its exits through the tailpipe.

When everything’s working correctly, this exhaust is colourless. But if something is amiss, you’ll see a cloud of smoke coming out of the back of your car.

There are three common colours of exhaust smoke emitted from a gasoline-powered engine:

  • White
  • Black
  • Blue/Grey or Grey/White

White Smoke

Most white smoke emission is normal which is a part of the combustion cycle which happens when the car is first started. Condensation turns into a vapour which can look like white smoke. As the engine warms up and the condensation dissipates the white exhaust smoke (steam) is no longer seen. If excessive white smoke is observed even after the engine warms up, there is trouble around the corner.


  • Coolant Leak: A telltale sign is seeing odourless white smoke along with low coolant level. Milky looking engine oil is also an indication which means that the coolant has found its way in the chamber and is being burnt. If your engine is overheating and you find yourself topping up the coolant very often, this can be a very close case.
  • Bad Fuel Pump Injector– When the fuel injectors go bad reducing the amount of fuel being delivered to the engine which causes white smoke from the pipes. This is a very common occurrence in diesel cars.
  • ECU Error: If the ECU or the Engine Control Unit malfunctions, it could very well tick-off the fuel timings causing inefficient combustion cycle leading to white smoke.

Black Smoke

Black exhaust smoke means the engine is burning too much fuel hence, The exhaust is spitting nothing but carbon.


  • The first thing you should check is your air-filter and other intake components like sensors, fuel injectors and the fuel pressure regulator.
  • Clogged fuel line: Black smoke is usually the easiest issue to diagnose and fix, but burning unnecessary fuel will definitely affect your fuel economy, so don’t think of avoiding this.
  • Carbonised Engine: This happens when the engine is clogged and packed-up with carbon. This required a complete engine de-carbonisation.

Blue/Grey or Grey/White Smoke

Anything other than white or black smoke is tough to diagnose, but if you see blue-grey smokes from your car exhaust, it is a sign that the engine is in distress.


  • Burning Oil: Like blue smoke, it can mean that the car is burning oil or suffering from a lousy turbocharger. Take the same precautions as with blue smoke, and check for excessive oil consumption.
  • Transmission Fluid Leak: Grey smoke can also be an issue with your automatic transmission fluid getting burned up in the engine. A faulty transmission vacuum modulator would be the culprit in this situation, leading to transmission fluid getting sucked into the engine and getting burned up.
  • Stuck PCV Valve: Grey smoke could mean a stuck PCV valve. The PCV system (Positive Crankcase Ventilation) cuts down on harmful emissions by recycling them back into the combustion chamber. However, when the PCV valve gets stuck, pressure can build and lead to oil leaks. Fortunately, PCV valves aren’t expensive and can be a quick job for a mechanic at a decent workshop.

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