The Reasons Why a Car Smells Like Rotten Eggs

Does your car smell weird? Well, it means that it’s trying to tell you about something off, something that is not going right. Just like the clicking sound of a bad CV joint or the rattling of a damaged timing chain, bad odors also indicate some issues. In fact, you should take all types of stenches, except for the fresh leather scent of a brand new car, as warning signs. What does it mean when your car smells like rotten eggs? Let’s find out.

Why a Car Smells Like Rotten Eggs?

A car smells like rotten eggs when the leftover deposits and byproducts burn up due to incomplete combustion. Here are some of the top reasons for this problem to happen and what you need to do about it.

1. Cracked Catalytic Converter

The converter is a part of the emission control components that reduce harmful emissions by modifying exhaust gasses. When they are busted, they cannot process the gasses, resulting in making your car smell like rotten eggs.

The only fix is to replace the converter. If it does not show any physical damage, you have to find out the thing that causes it to fail.

car smells like rotten eggs
The catalytic converter could be the reason. Source:

2. Malfunctioning Fuel Management Sensor

There is a sensor that controls the management of fuel in a vehicle. When it malfunctions, it cannot do its job properly. As a result, it injects too much oil, more than what the catalytic converter can handle. As a result, the converter cannot process the exhaust byproducts. When it runs rich for too long, the byproducts go to the tailpipe unprocessed and creates a very reeky odor. It is another reason why your car smells like rotten eggs.

A bad sensor can also make the catalytic converter overheated by sending too many byproducts to it. In that case, it will burn all the buildup and release a strong odor.

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3. Sulphur Deposits

Sometimes, deposits of hydrocarbons and Sulphur build up inside the catalytic converter. In that case, these things burn up and release the bad smell of rotten eggs when you rev up the car. If the odor does not linger more than the period of excessive use of the engine at high revs, there is nothing to worry. However, if the strong sulphuric stench does not go away or occurs at regular basis during normal use, you should check the fuel management sensor.

4. Old Transmission Fluid

car smells like rotten eggs
Old transmission fluid could be another reason. Source: Youtube

Sometimes, you can sniff sulfur (aka rotten eggs) when you forget to flush the fluids in the transmission and transfer cases and they somehow start leaking all over the places. It mainly happens in manual cars. Changing the fluids and repairing the hole or crack from where the fluid is coming out will solve this problem.

Tips to Remove The Smell of Rotten Eggs in Car

1. Vacuum The Interior in Car

Once the car smells like rotten eggs appears, most unpleasant these remain on the fabric fibers in the car. For these odors it is necessary to treat the vacuum cleaner several times, for the seats to use a suction nozzle.
You also need to pay close attention to every corner and small gaps because unpleasant odors may be hidden in the smallest areas. If you think the smell is not enough, use more water.

rotten egg smell from car
Vacuum car interior to reduce the rotten eggs smell in car. Source: HotCars

2. Baking Soda Powder

Baking Soda is always a good choice for deodorizing. If you dumped something on the rug to make the bad smell stay there, take the Baking Soda powder into place. Rub well and leave the carpet, Baking Soda powder will absorb any odor escape.
After a few hours, use a vacuum cleaner to drain the dough, and you will have a clean rug.

3. Deodorize with Natural Substances

Choose a spray with your favorite fragrance and spray it inside the car to hide the unpleasant smell. You can hang a cotton ball smothered vanilla inside the car. Or you can put a bag of coffee into the car to deodorize. Many people like to use the scent of mint or citrus oil.

4. Charcoal

Charcoal is one of the best absorbs for this car smells like rotten eggs situation. You will find that charcoal is used in many water purifiers and air purifiers. Get a lump of charcoal that can be used to bake for a few days, and you’ll soon see the smell disappearing as it gets absorbed in the coal.

why does my car smell like eggs
Using charcoal for reducing smell of rotten eggs in car. Source: Eater

5. Find A Professional Deodorizer

If you can not handle the unpleasant smell, think about bringing your car to a professional deodorizer. May be more expensive than homemade but the interior will be fully sanitized, the car interior will come back like new.


When your car smells like rotten eggs, you should not wait until the next maintenance visit. An overheated catalytic converter can melt inside if you keep driving and leave you with a more than $1,000 repair bill.