What Do I Do If I Have A Rotten Egg Smell In My Car?

What Do I Do If I Have A Rotten Egg Smell In My Car?

Anytime you smell rotten eggs in your car, it is a sign of potential issues. But to be safe, check your backseat to be sure you haven’t forgotten a few of last weeks’ groceries. Once you confirm that all your groceries are where you need to be, we can look into what is causing your rotten egg smell.

So what causes the rotten egg smell? Rotten eggs smell is a sign of sulfur reaching your cabin. It is a sign that your exhaust system is not converting fumes in your car into sulfur dioxide. If the process is working correctly, that means something in your vehicle isn’t working right.

Below, we are going to get into some potential causes for why your car smells like this. We will also get into some possible fixes that will help you ensure your vehicle stays in good condition.

X Reasons Your Car Smells Like Rotten Eggs

Below are some common reasons why your car may smell like rotten eggs.

  1. Malfunctioning catalytic converter
  2. Old transmission fluid
  3. Old or dirty fuel filter
  4. Broken fuel pressure sensor
  5. Your car has unburnt sulfur

If you need to go through any vehicle repair process yourself, always be sure to activate your parking brake and disconnect the battery of your car. In either case, it is good to know what is wrong before you bring it in.

#1: Broken Catalytic Converter

The most common reason for your exhaust releasing a rotten eggs car smell. The converter converts hydrogen sulfide into sulfur dioxide, which is typically odorless. This process makes sure that you aren’t breathing in any harmful fumes. If your catalytic converter brakes, it will not correctly convert the gases, releasing sulfur into your vehicle cabin.

At this point, you will need to replace your catalytic converter, which is not cheap. The average cost of a catalytic converter repair is $1500 but can cost up to $2500. If you have an older vehicle, the replacement of the catalytic converter may not be worth it. If you want to know how to replace the catalytic converter yourself, check out the video below:

#2: Old Transmission Fluid

When your transmission fluid leaks from your vehicle, it has a chance to release transmission fluid onto your other vehicle’s parts. The smell happens when your old transmission fluid begins to burn onto the different parts of your car. Leaking transmission fluid typically comes from the pan, but they usually come from age.

If you drive through gravel roads, rocks can fly up and pierce through fluid hoses and the pan. If it isn’t the pan, pay particular attention to aging seals.

If your hose is leaking, you can typically patch it up with some hose leaks. If you can’t locate the leak or it doesn’t seem easy to replace, you will want to bring it to a mechanic as soon as possible. It is unsafe to continue driving with leaking transmission fluid.

#3: Old Or Dirty Fuel Filter

As your fuel filter gets older, it won’t be able to process everything going to your exhaust. As a result, the high amount of unprocessed materials lead to the same effect as a failed catalytic converter. As your fuel filter gets clogged, you may also smell something burning.

Other signs of a clogged fuel filter include engine misfires, slow acceleration, and trouble starting the vehicle. You may also find your car stalling more often than usual.

While there is nothing unsafe from driving a dirty fuel filter, it can affect your vehicle’s performance. You shouldn’t drive on a dirty fuel filter for too long, as a stalled car on the highway can result in an unfortunate situation.

#4: Broken Fuel Pressure Sensor

A broken fuel pressure sensor leads to much of the same result as an old or dirty fuel filter. Suppose the sensor you have is unable to determine what level of fuel you need. If the sensor is malfunctioning, your vehicle’s fuel byproducts can lead to an egg smell in your car’s cabin.

Other signs of a failed fuel pressure sensor include a check engine light, problems starting your engine, low fuel mileage, and stalling. Given that it has the same crossover as the dirty fuel filter, it can be challenging to determine which of these two is the culprit.

As a result, try and locate a mechanic who knows what they are doing in this area. You can find the pressure sensor located on the fuel rail of your injection system.

#5: Car Has Unburnt Sulfur

Your vehicle may not have any actual problems with it. Instead, it comes from a combination of the car’s age and the fact that you haven’t revved it in a while. The catalytic converter has a high chance of just having the fuel build up.

Try and find a dirt road somewhere that you can slam down on the accelerator. After your car revs hard, some of the sulfur on the catalytic converter will naturally burn off. If you don’t drive your car like this every so often, this is an option.

It is more of an issue if you have an older vehicle. Newer vehicles don’t have this happen as often. Regardless, doing this can get some of the gunk out of your car.

How Much Does It Cost To Get The Rotten Egg Smell From Your Car?

To remove your car’s rotten egg smell, you may choose to detail clean your vehicle in the process. The cost of detailing your car can vary from $150 to $500, depending on what services you are willing to pay. Car detailers will not work on your exhaust system.

When referring to repairs, the cost of all of our different options can vary heavily. Below are what you can expect when paying for repairs.

  • Replacing your catalytic converter can cost anywhere from $1000 to $3000. As a result, a broken catalytic converter typically means you need to junk older cars. They are worth repairing in newer cars, which still have a lot of longevity.
  • The cost of replacing old transmission fluid averages at about $150. However, you can save almost $100 on this if you know how to replace transmission fluid yourself. Fixing a leaky transmission hose can cost about the same, but some repairs can be as high as $400.
  • The replacement of a fuel filter costs $15 to $60. You can add $50 to $150 for hiring a mechanic to do the work for you. This totals out the most you will pay for it at around $220.
  • The cost of a fuel pressure sensor replacement can be up to $250. This can vary heavily depending on the age of your vehicle. You can add another $200 for hiring a mechanic.
  • If you drive like a teenager for a couple of minutes, it typically doesn’t cost anything. But slamming into some wayward object costs a lot of money. So be sure that you pay attention.

Can I Safely Drive My Vehicle When It Smells Like Rotten Eggs?

If your vehicle smells like rotten eggs, many of the issues mentioned above can potentially stop your car from functioning at all. As a result, it isn’t a good idea to continue to drive your vehicle when you drive your vehicle.

If your car stalls or stutters on the side of the road, it can lead to you having to make an unfortunate call to roadside assistance. If you stall on the interstate, other vehicles may not notice you slowing down in time, leading to a potentially dangerous situation.

Are There Any Other Smells I Should Look Out For?

  • If your car smells like gasoline, that is a sign that you have a fuel leak somewhere. Look around your vehicle to see any signs of a fuel leak occurring.
  • If your car smells sweet, it is a sign that you have a coolant leak. Check your radiator, heater hose, thermostat, and water pump.
  • If your car smells like mildew, that means that you have it growing in your air conditioner. The buildup of moisture in your air conditioner can cause this if you don’t drive it often.


If your car smells like rotten eggs, it can come from a variety of different problems. However, the most common reason this happens comes from your catalytic converter. It may also be related to a poor fuel mix due to a malfunctioning sensor or dirty filter.

Whatever the case may be, it is your job to get this fixed as soon as possible. If left untreated, you could end up having your vehicle stop functioning entirely. As a result, either do it yourself or reach out to a mechanic who has the skill set.

Hiring a detailer also won’t help you out much if you don’t solve the underlying problem. Start with the practical solution and then move onto the deodorization process. Provided you use this guide, you will have a good idea of what you need to do.

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