How To Get Rid Of Rotten Egg Smell In Car?

There are many car owners who usually complain about rotten egg smell in car which comes out of nowhere. A sulphuric rotten smell that comes out of a car usually indicates an excess of byproducts that are left from failed combustion. Removing the smell might require the replacement of certain parts. This article discusses the different causes that result in a rotten egg smell coming out of the car so read on. 

What Is The Rotten Egg Smell In Car?

Imagine having a very unpleasant rotten egg smell in car. It would almost be impossible to sit inside the car and drive it. But what most possible do not know is that rotten egg smell in car can be an indication of a serious problem.

The smell usually comes out from the small amount of hydrogen sulfide, or sulfur, within the fuel. Hydrogen sulfide usually gets converted into odourless sulfur dioxide. However, when something breaks inside the vehicle’s fuel or exhaust system, it can put a stop to this process and create the pungent smell of rotten eggs. 

The byproducts and deposits that cause this smell are leftover from the incomplete combustion of gasoline that gets burned and can be traced to multiple system failures. However, if the rotten egg smell arose after the engine was used at high revs, then the issue may not be serious and it cannot be something that one must not be concerned about. A lingering rotten egg smell in car must be made to be checked by a trusted mechanic. 

What Are The Causes Of Rotten Egg Smell Inside Car?

There are mainly three common causes that cause a rotten sulphur smell inside the car.  Here are a detailed description of these causes. 

1. Broken Catalytic Converter

The most likely problem that causes the issue of rotten egg smell inside the car is a broken or faulty catalytic converter which is a part of the vehicle’s emission system. When gasoline enters the catalytic converter, it transforms the trace amounts of hydrogen sulfide into odourless sulphur dioxide. This converter is designed in such a way as to convert exhaust gases like hydrogen sulfide into harmless gases. However, a jammed, broken or faulty catalytic converter is incapable of properly processing the sulphur gases which will make your car smell like rotten eggs. 

If the catalytic converter is the cause of the problem, rotten egg smell inside the car, then you will need a new catalytic convertor. If your mechanic finds no fault in the catalytic converter, then there are two other issues that can cause the pungent smell. 

2. Failing Fuel Pressure Sensor Or Worn Out Fuel Filter

A fuel pressure sensor is responsible for regulating the use of fuel in a car. In the situation of a fuel pressure regulator failure, It results in the clogging of the catalytic converter with too much oi. Too much oil in turn will act as an obstruction for the convertor to process all byproduct products. This then exits the vehicle through the tailpipe which results in the production of a rotten egg smell. An excessive amount of byproducts can also build up within the catalytic converter which results in it overheating, also contributing to the smell. 

The replacement of a fuel pressure regulator or fuel filter can fix the issue in most situations. A worn-out or faulty fuel filter also results in the same problem as a faulty fuel pressure sensor, an influx of sulfur deposits burned up in the catalytic converter.

3. Old Transmission Fluid

It is important to occasionally replace old transmission fluid with new ones. If you missed transmission fluid flushes for a long time, the fluid will start to leak into other systems that can unleash the very pungent rotten egg smell inside your car. This however is typically only an occurrence that occurs in cars with a manual transmission. Changing the transmission fluid as recommended by your mechanic will help in solving the issue. Any leaks that may have appeared will also need a fix. 

What to Do to Remove The Rotten Egg Smell From Car?

From viewing the causes of rotten smell that comes from the car, it is evident that it is certain parts that cause this problem. To fix and completely remove the rotten smell from a car, it is better to fix or replace the part that causes the issue. The parts could be a catalytic converter, fuel pressure regulator, fuel filter or even old transmission fluid. The smell should disappear after the replacement of the faulty part. 

Some Other Common Smells That One Shouldn’t Ignore

Like how your car makes certain sounds or noises to indicate some problem, it also at times let out certain smells that indicate a serious internal issue. Here are some other common smells other than the rotten egg smell that you should never ignore. 

1. Hot Oil

This unpleasant smell that comes out of your car may be an indication of oil leaking onto the hot exhaust manifold. You may also notice a puddle of oil underneath your car. 

2. Syrup

Sometimes a sweet aromatic smell comes out of the car which may be the result of ethylene glycol in the coolant. It can be an indication of a leaky radiator or hose or a leak in the car’s heating system. 

3. Burned Carpet

The burned carpet smell maybe because of your brakes. With normal driving, the smell could indicate you have a dragging brake wearing down the pads, or you forgot to disengage your handbrake.

4. Burned Rubber

The burned rubber smell may be a result of a loose belt or a belt that is about to break.

5. Gasoline

This unpleasant odour is from sloppy refuelling. But it can also be an indication of a leak in your vent hose or fuel injection line. 


There are many smells that can occur in your vehicle depending on the issue it is having. Like there is this rotten egg smell that can come from the car, there can also be smoking or burning smells which can indicate serious engine overheating problems, a fluid leak or even worn-out brake pads. Ignoring the smells in the hope it going away soon, will never solve the problem. Such ignorance can only turn things from bad to worse. Seek the help of your trusted mechanic as soon as possible and do the necessary fix, once you notice a rotten egg smell or any smell coming out of your car.

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