Why Does My Car Smell Like Rotten Eggs : 10 Causes & Solutions

Rotten Eggs Smell in Car

The interiors of the vehicle are designed to give a comfortable and aesthetic look, to provide a comfortable ride for the occupants, and for easy cleaning of the inside of the vehicle.

But sometimes, as soon as you sit inside the car, the whole cabin starts smelling like rotten eggs. This smell can be felt anywhere in the entire interior of the vehicle. Due to this, it becomes difficult to travel and breathe in the vehicle. Through this article, we will know in detail what the causes of the rotten egg smell coming from inside the car are and how to get rid of it.

Causes of Rotten Eggs Smell in Car

If your car smells of rotten eggs, the causes may include a faulty catalytic converter, exhaust manifold leakage, faulty fuel pressure sensor, old transmission fluid, battery acid leak, wet floor mats, or a dead animal in the dashboard.

1. Wet & Damp Weather

This is the most common reason why a car smells like rotten eggs on rainy and cold days. Because in these days the weather is the most humid. Sometimes we wash the car, cover it, and lock it in our garage or parking lot for a long time. In that case, there is no air circulation inside the cabin of the car.

And during the rainy days, the weather gets more moist. Many a times, due to which due to washing the car from inside and due to high humidity during the weather days, fungus starts to accumulate in the closed cabin of the car and due to the accumulation of fungus and the lack of air circulation from the cabin of the car, the smell of rotten eggs starts coming.

2. Faulty Catalytic Converter

catalytic converter

The catalytic converter converts carbon monoxide, a harmful gas released from the vehicle’s engine, into carbon dioxide and converts hydrocarbons into carbon dioxide and water. simultaneously converts nitrogen oxides into nitrogen and oxygen.

But the catalyst becomes unable to convert the gases released from the engine or gets worse. Then the smell of gases coming directly from the engine starts to smell like rotten eggs. A faulty catalytic converter can also cause the car to smell like rotten eggs.

3. Dirty Cooling or Heater Coil

Clean evaporator coil

Whenever we run the AC or heater of the vehicle. Then the cold or hot air coming from the blower of the car passes through the cooling coil or heater coil to come to us. If your car’s cooling coil or heater coil has any kind of debris stuck in it.

Then this waste gets wet in the cooling coil or heater coil and gives off a foul smell. Due to which whenever we run the AC blower of the car. Then the coming air starts smelling like rotten eggs.

4. Exhaust Manifold Leakage


Sometimes a leak occurs before the gases reach the catalytic converter due to loosening of the exhaust manifold in the engine of the car or due to a malfunction of the gasket on the manifold. Due to this, the gases coming out of the engine get into the cabin of the car. Gases emitted directly from the engine can cause a rotten-egg smell in the cabin of your car. Therefore, leakage from the exhaust manifold can also cause a rotten egg smell in the car.

5. Faulty Fuel Pressure Sensor

symptoms of a bad fuel pressure sensor

There must be a fuel pressure sensor for the engine to run successfully. which sends a signal of the fuel pressure coming into the engine to the ECU of the engine. Based on which the ECU prepares the ignition timing and the firing order of the fuel mixture according to the position of the crank and piston of the engine.

And sends it to the combustion chamber of the engine, due to which the internal combustion process of the engine is successfully completed. But sometimes the fuel pressure signal does not reach the engine’s ECU when the fuel pressure sensor is faulty. Due to which the fuel does not burn in the right amount and the engine will have low performance and produce raw smoke. And the smell of raw smoke coming out of the engine can also make you smell like a rotten egg.

6. Dead Animal

Many times you must have seen a rat or a mouse roaming inside the cabin of the car or under the chassis, or any other small creature. But sometimes, for some reason, these small animals die in the cabin of the car and within a few days of death, it starts to rot. Due to this, more bad odor is created in the car’s cabin. This too can cause a rotten-egg smell in a car.

7. Rotten Groceries & Other Foods

Many times we take groceries in our car to home or any other place. Or it can also contain any other type of food item. But sometimes it accidentally gets hidden in the car after falling into some food items or groceries. Due to this, these hidden objects get spoiled or rot after lying like this for a few days. which starts producing a foul smell. This can also be the main reason for the smell of rotten eggs in the car.

8. Wet or Damp Floor Mats

Many times during rainy days, when taking the car outside, one has to get out of the car, due to which our shoes get wet again and again, and sitting inside the car with wet shoes causes water to seep onto the floor mats of the car or they can come inside with a window open during the rainy season. Due to which a strange smell starts coming due to excess moisture in the floor mats during the humid days. This can also cause a rotten-egg smell in the car.

9. Old Transmission Fluid

automatic transmission fluid pump

Whenever you have a vehicle with a manual transmission, Then according to the instructions of the vehicle manufacturer, you have to change the transmission fluid at the right time interval. Because if you do not do this, the transmission fluid gets spoiled and starts rotting.

Due to this, the transmission fluid starts leaking from many other places. and begins to freeze on the surface of the transmission. Due to this, the smell of rotten transmission fluid in the moving car starts coming into the cabin of the car. These factors can also cause a rotten-egg smell in the car.

10. Battery Acid Leak

Battery terminal corrosion

Many times the acid in the battery starts leaking when the electric battery used in the vehicle is old or the surface of the battery is broken by hitting something. which starts to settle around the engine in front of the car.

The acid used in the battery has a pungent odor. When the car can, this acid smell starts coming through the air in some way or the other in the cabin of the car. Battery acid smells like rotten eggs.

How To Check The Cause of Rotten Eggs Smell in Car?

Some of the common reasons you can check at home but if there is a mechanical reason for the smell of rotten eggs coming from inside the car. So for this, you may need to see a professional vehicle mechanic.

Checking Process

  • First of all, check for any dead mouse or rat or any other small creature inside the car. For this, you can check yourself. Or you can enlist the help of a professional vehicle mechanic.
  • Next, check the acid fluid of the vehicle’s electric battery. There is no acid leakage near the battery.
  • If this smell is caused by rainy days or damp weather, then for some time leave the car in the sun with the windows open. After this, you can hang any good perfume in the car.
  • Next, check the cooling coil and the heater coil. If you have any inconvenience doing this, then you can show it to the car mechanicing this, then you can show it to the car mechanic and also check the blower air filter.
  • Thoroughly check any food items in the cabin of the car; someone missed you by mistake some time ago.
  • Examine wet floor mats, and make sure that there is no moisture in the floor mats.
  • After this, you can get the catalytic converter checked by a mechanic.
  • And can also get the leak checked for engine exhaust manifold.
  • After this, the condition of transmission fluid and fluid leak can be checked.

How To Cure & Get Rid of Rotten Eggs Smell in Car?

To get rid of this, you can do some processing yourself at home. And to do some mechanical process, you can take advice and help of a professional mechanic.

  • If the smell of rotten eggs is coming from inside your car. And during checking you find any small dead animal/animal in your car. For this, take it out of the car and wash the car properly. After washing, park the car in an open environment during the day with the windows open. After this, hang some good perfume inside the car and close the windows.
  • If the smell of rotten eggs in your car is due to wet and damp weather, So for this also, you park the car during the day with the windows open in the sun, due to which the moisture inside the car will end. which was causing the smell in the car.
  • Take wet and damp floor mats out of the car. And open the car windows. And vacuum in the car. And after that, dry the floor mats completely and put them in the car again.
  • Inspect the car battery. Clean the fluid leak if battery fluid leaks out. If the battery is broken, replace it with a new one.
  • If the cooling coil and heater coil are clogged or dirty, have them cleaned by a professional mechanic. because the cooling coil and heater coil are located deep inside the dashboard of the car. You can’t clean it yourself.
  • Clean the clogged catalytic converter or replace the bad catalytic converter with a new one.
  • Check and fix the leak in the engine exhaust manifold.
  • Check the condition of the transmission fluid, replace it with a new one if the transmission fluid is damaged. And also fix the leakage of transmission fluid


Q. Is the rotten egg smell in my car dangerous?

Yes! A simple egg-like smell in the car cabin can be injurious to your health. Because usually this smell is caused by the toxic gases coming out of the engine fumes reaching the car cabin. A rotten egg smell can result from a vehicle engine failure, fuel, exhaust system or catalytic converter failure.

Because the toxic elements released from this smoke are carbon dioxide, hydrogen sulfide, and nitrogen oxides. Therefore, when we breathe, these elements can have a bad effect on our health.

Q. What If My Car Smells Rotten Eggs And Won’t Start?

If your car does not start and it smells like rotten eggs, So chances are, there is a problem with your car battery. A car battery can get damaged in a number of ways. for example, battery cracking, acid fluid leaking, battery shorting, etc.

Q. What is the reason for the smell of rotten eggs in the car when the car is accelerating?

When we give acceleration to the engine of the car, Then a large amount of smoke comes out of the exhaust of the engine. if the catalytic converter of your car’s exhaust system is clogged or bad and fails to convert the toxic gases released from engine fumes. Then the sulphur dioxide gas released from the engine smoke starts entering the cabin of the car. due to which a rotten-egg-like smell starts coming from inside the car.

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