Is White Smoke From Exhaust Normal?

If you own a car, you’d know how it should behave when it’s in use and what signs indicate it’s time for a trip to the mechanic. For instance, you’d pay attention when fumes and smoke come out from the exhaust. Exhaust fumes are a natural function of the vehicle, but what happens when the fumes are an irregular color or smell?

White smoke coming out of the exhaust is normal in colder weather. However, persistent white smoke could be a sign of an underlying issue. You should consult a mechanic if white smoke is frequent, particularly if there’s a smell with it.

Although white smoke from the exhaust is harmless in some instances, ignoring a persistent white smoke might damage your car engine. This article will explain why white smoke comes out of the exhaust and how you can fix the underlying causes.

Causes of White Smoke From the Exhaust

White smoke comes out of the exhaust if there’s condensation. However, internal problems with the car like a damaged cylinder head, coolant or oil leak, a malfunctioning fuel injector, a faulty engine control unit, or a cracked engine block can also cause white smoke from the exhaust.

Read on as I explain why white smoke can come out of the exhaust.


A light or thin white smoke coming out from the exhaust is normal on a cold day when warm or hot exhaust gasses meet the cold air outside and produce steam. When you start your car engine on a cold day or accelerate, this steam comes out as thin, white smoke from the exhaust pipe.

It’s water vapor and is nothing to worry about. It should clear up within a minute.

Often drivers and car owners who have lived in warm climates tend to get anxious when they move to colder regions and see white smoke from the exhaust.

However, if white smoke continues to come out from the tailpipe after your car has warmed up for a couple of minutes, something is wrong with your vehicle.

Damaged Cylinder Head

A cracked or damaged cylinder head causes the coolant to leak. When coolant leaks out, it mixes with engine oil and contaminates it.

White smoke coming out from the exhaust is the first sign of contaminated engine oil. If the problem isn’t fixed soon, the white smoke will start emanating a sweet smell.

A cracked cylinder head can also cause exhaust gasses to flow back into the cylinder heads. This produces white smoke that comes out from the tailpipe.

Damaged Coolant Tank

A cracked or damaged coolant reservoir tank can cause the coolant to leak out.

Damage to the coolant reservoir tank is a rare issue. However, someone can accidentally damage the tank while working on the car to fix another problem.

A damaged or cracked coolant tank needs to be fixed right away.

Leaky Head Gasket

The head gasket is the seal between the cylinder lock and cylinder head in an internal combustion engine.

A leaking head gasket causes coolant to seep into the cylinders. The coolant gets heated and blows out of the exhaust in a steady stream of thick white or gray smoke.

One way to confirm that you’ve got a leaking head gasket is to check the coolant level in the reservoir. If the level is low and you don’t see coolant leaking anywhere else, you can be sure that you’ve a cracked head gasket.

While checking the coolant level, ensure that the car is not running. Remove the coolant reservoir cap only after the car has cooled down.

If the coolant level is normal, you have to check the cooling system pressure to find out the source of the leak.

Besides the smoke, a coolant leak can overheat the engine and stall your car, especially in summer. Worse, you can damage the car engine if you don’t fix the leak and continue to run the car.

You must never ignore a leaky head gasket. You can try to seal the leak with a head gasket repair and treatment kit.

The K-Seal ST3501 Head Gasket (available on Amazon) is made from a unique blend of chemical ingredients that “seeks out” holes and cracks in the coolant system and seals them permanently. It’s easy to use and works for most leaks in water-cooled engines.

The Bar’s Leaks 1100 Head Gasket seals cracked cylinder heads and blocks and repairs blown head gaskets. Its unique blend consists of liquid ceramics and reinforced fibers that can penetrate large and small cracks to seal them permanently.

When using the Bar’s Leaks Head Gasket Repair, remember to flush out and remove the antifreeze from the cooling system before adding the sealant.

Oil Leak

If motor oil leaks out from the piston rings or valve seals, it flows into the internal combustion chamber and mixes with gasoline and air.

Oil mixed with gasoline and air causes bluish smoke to come out of the tailpipe. However, the smoke can appear white to some people.

This is a serious issue that can trigger other problems if not fixed right away. When oil leaks, the engine components are not lubricated to the extent they’d. This causes them to wear out quickly.

If you continue to run your car with an oil leak, the wear and tear of the engine components accelerate and trigger other mechanical issues that are expensive to fix.

Injector Pump Timing Is Off

This is an issue with vehicles that run on diesel.

The injector pump supplies diesel to the cylinders. The fuel has to be supplied just when the engine needs it. Otherwise, there can be an overrun of diesel that can produce thick, white smoke from the exhaust.

Contaminants in diesel can cause the injector pump to malfunction.

To fix this issue, you may have to do one of the following:

  1. Reprogram the ECM.
  2. Replace the camshaft.
  3. Replace the injector pump.

Malfunctioning Fuel Injector

A malfunctioning fuel injector can’t regulate the amount of fuel that goes into the internal combustion chamber. This causes white smoke to come out from the exhaust.

A fuel injector malfunctions if there are contaminants in the fuel. The only way to fix a faulty fuel injector is to replace it. However, you must replace the whole set of injectors instead of only one.

A fuel injector may also not work correctly if it’s clogged.

Faulty Engine Control Unit

Sometimes the engine control unit can develop a glitch in the programming. The glitch can prevent it from regulating the time of the fuel injector. As a result, the fuel injector malfunctions even though there are no mechanical issues.

If you suspect that a faulty engine control unit is behind the thick white smoke, you can try to fix the issue by unplugging the car battery to reset the computer. The problem might fix itself.

However, if this strategy does not work, you must visit your dealership, where expert mechanics can reprogram the engine control unit.

Damaged Engine Control Block

Overheating of the engine can cause the engine control block to crack. Overheating is usually caused by an issue with the coolant.

Sometimes the water pump can fail and prevent the coolant from flowing through various parts of the car’s system. This can cause the engine to overheat.

A cracked engine block causes oil to leak into the combustion chamber. The leaked oil then mixes with fuel and air and starts to burn. Burning produces white smoke that is sucked out and emitted through the exhaust.

The following are three methods of fixing a cracked engine block:

  1. Re-weld it.
  2. Use a cold-metal patch.
  3. Carry out cold-metal stitching.

Can I Drive With White Smoke From the Exhaust?

You shouldn’t drive with white smoke from the exhaust if the fumes aren’t produced due to condensation. Thick white smoke coming out from the exhaust in a steady stream is a sign that coolant is leaking into the combustion chamber. Running the car in such a state can cause the engine to overheat.

Take your car to a professional mechanic. They’ll inspect the vehicle to figure out and fix the problems that might be causing white smoke to come from the exhaust.

Regular inspection and maintenance are critical to ensure that any problem with your car’s system is spotted early and fixed promptly.

Final Words: Be Aware of the Signals Your Car Is Sending Out

Car ownership comes with several responsibilities. You have to ensure that your car is in peak condition and performing optimally. And for this, you must be able to spot and identify the signals your car sends out when it’s distressed.

White smoke from the exhaust can be a symptom of several underlying issues with the car’s systems. Besides risking engine damage, these issues cause your car to consume more fuel than usual.

Paying attention to warning signs like white smoke from the exhaust prevents costly repairs and ensures your car remains fuel-efficient.

Related: How to Make Your Exhaust Louder

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