What Does White Smoke From My Exhaust Mean – Is It Bad?

We have listed the eight reasons in order of repair cost, starting with the cheapest, which will cost nothing, up to the most expensive repair, that’ll cost thousands of dollars.

The most common reasons for white smoke to be seen coming out of your exhaust are condensation being burned away, coolant in the engine via a cracked engine block, or a blown head gasket.

1. Damp Mornings and White Exhaust Smoke

Bear with me on this one! I know it’s a long shot, but people have been caught with this.

Modern gasoline engines shouldn’t emit visible tailpipe emissions if running correctly.

There is only one exception to this rule: when your car has been left stationary overnight when the weather is cold and damp.

In the same way, you can see your breath when it is cold; you may also see white smoke when your car starts up when it is cold. This is because water condensation builds up in the exhaust pipes and burns off as your car warms up. 

It’s not even white smoke, but it can look like this. There is nothing to worry about. As the water vapor burns away, the white-looking smoke will stop. After driving for 5 minutes, it shouldn’t be noticeable.

There is no cost or repair needed.

The following seven reasons why white smoke comes from the exhaust require further investigation and shouldn’t be ignored.

2. Overfilled With Oil 

Have you or a mechanic topped up your oil level, and you’re seeing white smoke from the tailpipe for the first time? If so, the cause of the white smoke is probably that there’s too much oil in the engine, and it’s being burned away.

When you can, pull over and stop the car. Wait 20 minutes until the oil level has settled, and take a dipstick reading. If it’s above the maximum point, you have too much oil. 

If so, you shouldn’t drive the car. Call a mechanic, and he can drain away the excess. If you use the vehicle, you may cause damage to spark plugs, resulting in a build-up of pressure and blowing the gasket seal in your engine.

If you have just returned from having your car checked over, the garage may tell you that the excess oil will burn itself off in time. Insist that you want it drained away instead for the reasons above.

You can drain the excess oil by removing the plug underneath the engine. However, judging is difficult, and you may drain away too much by mistake.

A mechanic will charge $50 in labor to drain the oil away.

3. Damaged Coolant Reservoir Tank or Pipes

The coolant reservoir tank and associated pipes are areas where coolant can leak. The excess water and coolant must go somewhere and find their way out of the exhaust pipe. The exhaust pipe is very hot, turning the liquid into white smoke and burning it off. 

You may also smell a sweet fruity smell from the exhaust, which is the smell of the coolant that can’t be burned off as quickly as it has a slightly higher boiling point than water.

This can happen when a mechanic fixes another problem on the vehicle and damages the tank.

Turn off your engine right away. Your car needs coolant to take away the heat from the engine. Without it, your engine can overheat and have to be replaced.

If you stop the car quickly enough, this is quite a cheap repair.

Expect to pay no more than $150 for a mechanic to find the source of the leak and repair it.

4. Oil Leaks

If oil leaks from your valve seals or piston rings, it will flow along with the fuel into the internal combustion chamber. The fuel and oil will eventually mix.

Although the smoke will be blueish-ish, some people will see it as white.

This is why you’d want to fix the leak quickly. If the oil isn’t used properly, the engine components will wear out and get damaged. This could lead to other costly problems that you don’t want. 

Stop your car and then pop the hood when the engine has cooled down. Look inside around the engine and look for signs of oil leaking. If an oil leak is a reason for the white smoke, it just might be noticeable. If you have checked your oil level recently, recheck it as if it has gone down; it’s a sure sign of an oil leak.

Generally, though the smoke from the exhaust is a sign of an internal leak – you’re unlikely to see oil leaking from the engine unless there has been a catastrophic failure.

If the oil leak is coming from a gasket, then the parts are a cheap fix but if it’s leaking from the piston rings, expect to pay a lot more. Most of the costs will be labor charges.

5. Engine Control Unit Error

A faulty or malfunctioning engine control unit can cause the timing of your fuel injector to be off. This doesn’t mean that the fuel injector has gone wrong. This means that the engine control unit must be repaired or reprogrammed to correct the timing of the fuel pump injector.

Sometimes, the problem can be fixed by simply unplugging your car’s battery for a few moments to reset it. Your dealer will need to do the job if this does not work. 

Expect to pay around $70 for an ECU check. If it highlights other repairs, this cost could rise significantly.

Is your car idling at a higher speed than normal? It could be connected.

This article may help, Is My Car Idling To High, Consequences and Fixes

6. Bad Fuel Injectors

The fuel injector controls the timing of fuel entering the combustion chamber. Bad fuel injectors can cause white smoke because the correct amount of fuel is not entering the chamber at the appropriate time. This can happen when they become clogged with carbon.

They should last 80,000 miles, but this period can reduce if a car hasn’t been tuned regularly. You can add a fuel injector cleaner to your fuel to see if this fixes the white smoke. 

A new set of fitted fuel injectors will cost from $1,000 – $1,500, including labor. The parts will cost between $500 to $700, and the labor costs between $500 and $800 depending on the make and model of the car.

7. Cracked Head of the Cylinder

The head cylinder is the top part of your engine. Coolant can leak from a cylinder head if it is damaged or cracked. It doesn’t have to be a large crack. It takes a small amount of coolant to leak and mix in with the engine oil.

Oil will then become contaminated. White exhaust smoke from the tailpipe is the first sign of this. The white smoke will continue and develop a sweet odor that won’t disappear.

A replacement head cylinder costs $2,000 to $5,000, including labor. Luckily, it’s very rare for the head cylinder to fail this way.

8. Cracked Engine Block

The engine block is the bottom part of your engine. Worst case scenario, your entire engine block is cracked. 

These problems are the most expensive to fix, and you’re likely to be without your car for 10+ days while the repair takes place. 

The high repair cost and labor sometimes prompt owners of older cars to scrap them as the repair costs more than the car’s value.

Luckily, this is a rare cause of white exhaust smoke.

Often read next by other visitors: Why Does My Car Smoke At High RPMs? Blue, Black or White [GUIDE]

In Conclusion

Always park up if you see white smoke coming from the exhaust if you think it might not just be condensation burning off.

The most likely reasons you’ve got white smoke from your exhaust are the cheapest to fix. 

It’s always best to get your car checked out as it won’t suddenly stop, and you may be doing further damage by continuing to drive it.

Have you noticed your steering becoming less responsive and feeling like locking up?

Check out our Steering Wheel Locking Article

Have you got Black exhaust smoke instead? It could mean something completely different.

Read Our Complete Guide To Signs and Symptoms of A Bad Fuel Pressure Regulator