Engine Maintenance

White smoke from exhaust – causes and fixing it

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If there is white smoke coming from the exhaust of your car, it might mean that there is an underlying issue that needs fixing. Let’s talk about when to get worried and what are the possible causes of a modern engine to emit a lot of white smoke.

But first: is the smoke from your car’s tailpipe supposed to be white?

Well, when a car engine is running as it should, at the proper operating temperature, you shouldn’t notice anything coming out of the tailpipe.

What causes white exhaust smoke?

The possible causes of white exhaust smoke, especially when accelerating, are:

  • condensation in the tailpipe
  • oil leak
  • piston ring or valve seal leak
  • a bad fuel injector
  • cracked cylinder head or bad head gasket
  • cracked engine block
  • ECU – engine control unit error
  • a bad EGR cooler

While the first cause is nothing to worry about, the rest mean that your car’s engine needs to be serviced – and you should that sooner than later.

Let’s talk about each of the possible causes and see how you can fix them.

White smoke from condensation

When it’s cold outside or colder than usual, and you crank up your car, white smoke might come our from the tailpipe.

If this happens, don’t worry! The smoke is simply a result from the hot exhaust gasses meeting the cold air. And it should go away after a short period of driving, as your engine and car’s parts reach operating temperature.

People who are used to living in a warm climate like California and leave or move to a colder region might experience this white smoke.

It is harmless, so don’t worry!

Oil leak

Oil leaks that come from your engine’s pistons and valves into the combution chamber. There, it mixes with fuel before coming our of your tailpipe. But do take into account that this will make the smoke look white but has a blue tinge. This is because oil changes its chemical composition when exposed to the high temperatures that exist in the engine.

This one is quite hard to diagnose, so you might want to take your car to a mechanic if you don’t know what you are doing.

A piston ring or valve seal leak

While we’re talking about white and light bluish smoke coming out from the exhaust, piston rings and valves are another possible cause. It’s the same concept: oil leaks into the combustion chamber.

If you’re planning to DIY this sort of job, be sure to consult a service manual for your car make and model. And take your safety precautions.

A bad fuel injector

White or grayish smoke from your tailpipe might also indicate that you have a faulty fuel injector. Faulty, in the sense that it’s leaking. When a fuel injector delivers too much fuel to the combustion chamber, the excess cannot fully burn in the engine and finally comes out as smoke.

If you are willing, you can probably test these yourself. Also, you could try a fuel injector cleaner. There are some pretty good products out there that might just do the trick!

Cracked cylinder head or bad head gasket

If even after driving for a long time, and the car is probably at operating temperature or close to it, and your car keeps emitting white smoke, you might have a cracked cylinder head – leaking coolant.

You don’t need to have a big crack. All you ‘need’ is a little bit of coolant to leak out and get mixed with your engine’s oil.

Once the coolant mixes with the engine oil, the oil will become contaminated. The first sign of this thing happening is white exhaust smoke coming out from the tailpipe. And as this continues the white smoke will begin to have a sweet odor smell that won’t go away.

Other signs might be: bubbling in the radiator and coolant reservoir, milky white coloration in the oil and even engine overheating.

A proper inspection of the cylinder head might reveal if this is the case.

Cracked engine block

This is the worst case scenario, and to be fair, the rarest. Not to panic you or anything but you need to know all the possible causes of white smoke coming out of your tailpipe. In most cases of a cracked engine block you won’t be able to tell until you have a mechanic look over your engine and perform a diagnosis on it.

Fixing this ain’t cheap. And if the car in question is old or cheap, it might be time to consider an engine swap or even replacing the car as some jobs can go uploards of 3000$ for something like this.

Engine Control Unit Error

The ECU might have a glitch. It is entirely possible for it to throw off the timing of the fuel injectors. This doesn’t mean that the fuel injectors are bad or something like that. It just means you need to fix or reprogram the ECU (short for Engine Control Unit) so that it can correct the timing of the fuel pump injector.

Often, you can get away with a cheap fix: just unplug your car battery for a few minutes to reset the computer and the issues disappear. But if the issue persists, and you don’t suspect any of the above issues, you might need to go to your dealership or a mechanic who is familiar with your car make and model to get this done.

A bad EGR cooler

A failing EGR cooler emits white smoke, or steam. This is caused by the evaporating coolant inside the cooler. If your car comes equiped with an EGR cooler, it might just be it!

While it is an issue and it should be fixed, on a lot of car models it’s really not that hard to DIY this one. Look for a guide or just take your car to a mechanic if you’re not feeling too confident.


As you can see, a lot of the causes revolve around your engine’s coolant liquid. If you notice that the coolant level keep dropping, and you have white smoke coming out of your tail pipe even if the car is running for a while (more than a couple of minutes), be cautious and inspect your engine for the above possible faults. The sooner you fix these kind of issues the better.

Final thoughts

Basically, the only time you don’t have to worry about the white smoke is when it clears up within a couple of minutes of starting your engine. If the white smoke stays on longer than that, then you need to find out the cause and fix it in order to have your engine run as it was intended by its manufacturer.

Car enthusiast. I am dedicated to maintaining my cars as best as I can. I love things that work, and I love keeping them in a good state.

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