Last Updated on April 8, 2023 by Chase Manhattan
Some fleeting odors like gas and fuel are expected and normal. Usually, these odors are nothing to be worried about and are not a sign of a faulty part. The smell of rotten eggs and sulfur is definitely something to worry about and should be investigated. Why does my car smell like rotten eggs?
The smell of rotten eggs and sulfur in a car can be caused by a faulty catalytic converter, a faulty fuel pressure sensor, or a transmission fluid leak.
A sulfur odor is not only a sign that your car has a faulty part but it can also be poisonous. So, you don’t want to inhale the gas for extended periods. That’s why you need to fix what’s wrong with your car as soon as possible. But first, you need to find out what’s wrong with it.
Here are the reasons why your car smells like rotten eggs.
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Bad Catalytic Converter
As the name suggests, the catalytic converter converts harmful toxins into less harmful ones. Cars release a lot of toxins that are bad for the environment and you. The catalytic converter reduces emissions. It converts those bad gases into byproducts that are not as harmful or not harmful at all. [Source]
It’s connected to the car’s exhaust pipes. You can see it if you take a look at the undercarriage. The converter is a cylinder. Just look for a cylinder connected to the exhaust pipes.
A gas that the catalytic converter is supposed to neutralize is hydrogen sulfide. Typically, it would convert that hydrogen sulfide into sulfur dioxide. Hydrogen sulfide has a strong odor, it smells like rotten eggs. Sulfur dioxide is odorless, and not harmful at all.
You are getting where this is going, right? When there is a fault with the catalytic converter, it won’t be able to convert the hydrogen sulfide into sulfur dioxide. This will result in your car smelling like sulfur or rotten eggs.
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Signs Of A Bad Catalytic Converter
- Weak engine performance.
- Struggle to accelerate.
- Rotten eggs smell.
- The car heats up, especially the undercarriage.
- Black smoke coming out from the exhaust.
[Related Article: How To Get Smoke Smell Out Of Car]
Transmissions Fluid Leak
Another thing that may be linked to the rotten eggs smell in your car is the transmissions fluid. The purpose of the transmissions fluid is to lubricate the parts inside the car’s gearbox. The gearbox has a lot of metal parts that grind against each other when they turn.
The transmission fluid lubricates the metals and bearings to prevent grinding. Unfortunately, that fluid can sometimes leak outside the gearbox. And when that happens, it can cause multiple issues with your car. Most importantly, it will release the smell of rotten eggs.
Usually, the transmission fluid will leak because of cracks in the fuel lines, cracked torque pump, and cracked axle seal. You will have to visit a mechanic to find out why the transmissions fluid is leaking.
Signs Of Low Transmissions Fluid
- Struggling to shift gears.
- Burning smell or smell of rotten eggs.
- Buzzing noises or roaring when you accelerate.
Bad Fuel Pressure Sensor
That bad odor you are smelling may be due to a bad fuel pressure sensor. Cars that run on petrol or diesel have a fuel pressure sensor. It monitors the pressure of the fuel system. If there’s anything wrong with a leak in the fuel system, it sends information to the car’s computer. [Source]
The computer makes adjustments to the fuel system and the car’s timing. If the sensor malfunctions the car’s performance will be affected. The engine will stall, the car will waste more fuel, and the check engine light will be on.
A faulty fuel pressure sensor can mess up the catalytic converter as well. As already mentioned, a bad converter will result in a rotten eggs smell. The sensor isn’t directly responsible for the sulfur odor but it affects the catalytic converter.
Signs Of A Bad Fuel Pressure Sensor
- The car will have problems starting.
- The car will struggle to accelerate.
- Engine stalling.
- The check engine light will be on.
- Bad fuel economy.
Food Left In Car
Lastly, I want to point out something obvious. I believe most of you check for this but just to be sure we’ll mention it. Before you go checking these parts that actually need a mechanic to be repaired, check for any food in your car.
Certain types of food smell like rotten eggs when they go bad. Just check every nook and cranny of your car, especially for food that has eggs in it. If you find food, that is why your car smells like rotten eggs.
If there is no food in your car, then check for the causes we already talked about.
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What Do You Do If Your Car Smells Like Rotten Eggs
The first thing to do is figure out why your car smells like rotten eggs. Since this task is hard enough to do, I recommend visiting a mechanic as soon as possible. Chances are you will have to repair the catalytic converter. Or, you will have to fix the transmission fluid leaks.
Also, you may have to fix the fuel pressure sensor. All of these things require a mechanic to be fixed.
Related Questions And Other FAQs
Can I Drive My Car If It Smells Like Rotten Eggs
You shouldn’t drive your car if it has a persistent smell of rotten eggs. The sulfur odor is a sign of a faulty catalytic converter, transmission fluids leak, or a faulty fuel pressure sensor. Driving your like that may lead to further damage or you inhaling taxes that are harmful.
Why Does My Car Smell Like Rotten Eggs When I Turn The AC On
When the AC filter clogs up, dirt, moisture, and debris fill up. This will result in mold and mildew growing inside the AC if not cleaned fast enough. The AC will still work but it will smell like rotten eggs. A clogged AC filter doesn’t necessarily smell like rotten eggs, it can have a foul odor or a musty smell.
