Picture this:
You’re driving down the street when you’re suddenly hit with an unexpected stench of rotten eggs.
Unless you’ve forgotten to take out old grocery bags, this unpleasant smell might come from your car’s components.
But don’t worry!
In this article, we’ll help you figure out what makes your car smell like rotten eggs and how to get rid of it. We’ll also show you how to avoid this odor.
This Article Contains:
- 4 Reasons Why Your Car Smells Like Rotten Eggs
- How to Identify the Source of Rotten Egg Smell?
- How to Get Rid of the Rotten Egg Smell from the Car?
- How to Prevent Your Car From Smelling Like Rotten Eggs in the Future?
- Is It Safe to Drive a Car That Smells Like Rotten Eggs?
- What Are Some Other Common Car Smells?
4 Reasons Why Your Car Smells Like Rotten Eggs
Let’s investigate the reasons behind this unusual smell:
1. Faulty Catalytic Converter
A catalytic converter turns harmful chemicals such as hydrogen sulfide, which causes the rotten egg smell, into odorless sulfur dioxides that leave the car as exhaust fumes.
But the catalytic converter can get clogged with unburned fuel and carbon deposits, especially if the engine runs rich. When that happens, the catalytic converter won’t be able to properly convert hydrogen sulfide into sulfur dioxide, making your car smell like rotten eggs.
2. Malfunctioning Fuel Pressure Sensor
The fuel pressure sensor regulates the flow of fuel into the combustion chamber.
If it fails due to electrical issues or wear and tear, it can send too much fuel into the engine, creating a rich air-fuel mixture. This excess fuel will then pass through the exhaust system and end up in the catalytic converter.
However, the catalytic converter isn’t designed to handle the excess fuel. So, it won’t be able to convert the harmful gases, resulting in sulfuric gas emissions and the rotten egg smell.
Note: A bad fuel pressure regulator, fuel injectors, or fuel filters can also cause this issue.
3. Battery Issues
Car batteries typically contain sulfuric acid, which stays safely within the battery case.
If the battery gets damaged by physical impact or exposure to extreme temperatures, the acid can leak out. This leak causes a funky odor, which is noticeable when you open the hood.
Additionally, overcharging a battery can release gases like hydrogen sulfide, which has a similar rotten odor.
4. Old Transmission Fluid
Older cars sometimes use sulfur-based transmission fluid. If you don’t change your transmission fluid around every 50,000 miles, it can wear out the seals and cause leaks.
In case the leaking fluid drips onto hot engine components, it can produce a strong rotten egg odor.
Now that we’ve listed the suspects that make your car smell of rotten eggs, we’ll find out how to narrow down its cause.
How to Identify the Source of Rotten Egg Smell
As a car owner, it might be difficult to diagnose the problem yourself, as it requires the necessary equipment and know-how. So, it’s best to get help from a qualified mechanic.
Here’s what a mechanic will do:
- Monitor the engine temperature: The cooling system should maintain the engine temperature between 190 and 225°F, or the needle should point to the middle of the temperature gauge. If the engine runs too hot, it can damage the catalytic converter, making it difficult to convert hydrogen sulfide and cause an unpleasant smell.
- Check battery condition: Inspect if the battery case is swollen or has fluid on it.
- Look at the dash for a flashing check engine light: If there is a lit check engine light, the auto mechanic will scan the engine for trouble codes to check which malfunctioning part triggered the CEL.
- Check engine and transmission fluid levels: They’ll check fluid levels with a dipstick and detect fluid leaks using fluorescent dye and UV light.
- Blow air through the fuel filter inlet onto a rag: Easy airflow means it’s clear, while resistance indicates a clog.
- Use an exhaust gas analyzer: They’ll check for excessive hydrogen sulfide, indicating a faulty catalytic converter.
Next, we’ll explore ways to get your car smelling fresh again.
How to Get Rid of the Rotten Egg Smell from the Car?
An auto mechanic would have to repair, replace, or clean the component responsible for the problem to eliminate the bad smell. These can include:
- Fuel filters: Remove the dirt and grime. If there’s too much buildup, the mechanic will replace the filters.
- Transmission fluid: Flush the old transmission fluid and replace the seals.
- Battery: Replace the broken battery. For an overcharged battery, remove the electrolyte, fill it with a mix of Epsom salt and distilled water, then recharge at a low voltage.
- Catalytic converter: Use a catalytic converter cleaner to remove contaminants. But if the catalytic converter is damaged, they might repair or replace the part.
- Fuel pressure sensor: Replace the sensor if it’s malfunctioning. If it’s an error in the engine control module (ECM), they’ll disconnect the battery for a few minutes to reset the ECM. Then, they’ll reconnect the battery to see if the problem is resolved.
Note: After the components are fixed, you can deodorize your car by placing activated charcoal pouches.
Next, we’ll cover some ways to prevent your car from smelling like it’s been snacking on rotten eggs.
How to Prevent Your Car From Smelling Like Rotten Eggs in the Future?
These are a few things you can do to ensure that unusual smell doesn’t creep up again:
- Avoid aggressive driving, such as heavy braking and sudden acceleration, as these habits can lead to inadequate combustion.
- Change your car’s fuel filter every two years or 30,000 miles.
- Use high-quality fuel with low sulfur content to reduce emissions.
- Schedule regular exhaust system checks for leaks, damage, or rust.
- While checking out certified pre-owned vehicles, take a test drive to detect any malfunctioning parts, which could cause a rotten egg smell. For example, a rattling exhaust can indicate a faulty catalytic converter.
Wondering if you can drive your car with a rotten egg smell?
Keep scrolling to find out.
Is It Safe to Drive a Car That Smells Like Rotten Eggs?
No, it’s not recommended to drive with a rotten egg smell. Here’s why:
- A clogged catalytic converter creates excessive exhaust backpressure, which leads to poor fuel economy and reduced power. Over time, this problem can lead to a costly engine repair.
- Leaky car batteries can damage engine components like the starter and alternator, as the acid corrodes the metal and plastic. Additionally, the battery poses a risk of explosion from hydrogen gas.
- Hydrogen sulfide gas is highly toxic and can irritate the skin while also affecting the nervous as well as respiratory systems. Prolonged exposure can lead to dizziness, difficulty breathing, and even coma.
However, the rotten egg smell isn’t the only bad smell your car can produce. It can also cause a musty smell, a sweet smell, a burning rubber smell, and more.
What Are Some Other Common Car Smells?
As a car owner, you should be wary of these odors as well:
- Burning plastic smell: A burnt electrical fuse or overheating AC compressor can scorch the nearby plastic components or wiring, leading to this peculiar burning smell.
- Burning rubber smell: Worn-out belts, hoses, or brake pads can give off the smell of burned rubber as they heat up due to friction.
- Burning carpet smell: When the brake pads or rotors overheat while braking, they produce a smell similar to that of burned carpet.
- Gas smell: A leaky fuel tank, fuel injector, faulty gas cap, or an engine misfire may cause this odor.
- Musty smell: Mold or mildew in the AC can cause excess moisture, making the car feel damp inside.
- Sweet smell: When the coolant leaks, it produces a distinct odor that is like maple syrup.
Clear Out the Rotten Egg Smell with AutoNation Mobile Service
A rotten egg smell can be quite unpleasant, not just for you but for your car as well.
Want to get out of this stinky situation quickly?
AutoNation Mobile Service can help.
We’re a mobile auto repair and maintenance solution that offers upfront pricing and easy booking. We also provide a 12-month | 12,000-mile warranty on all services, such as diagnosing a burning smell, brake repair, and engine repair.
Contact us, and our mechanics will fix your car’s odor issue from your driveway.