4 Reasons Your Car’s Bad Smell Could Indicate a Serious Problem


4 Reasons Your Car’s Bad Smell Could Indicate a Serious Problem


What Are The Main Reasons Behind a Vehicle’s Bad Smell?

Is your car smelling weird recently? There may be something wrong with your vehicle if it smells like rotten eggs, so you should fix it soon. Besides, this sulfur smell is quite harmful to your health.

But what are the main reasons behind a vehicle’s bad smell? In this article, we will explain the four most common to give you an idea. Take note of them before calling your Mesa car maintenance company.

4 Reasons Your Car's Bad Smell Could Indicate a Problem

Check Inside Your Vehicle First

Although absurd, you should ensure you didn’t forget eggs in the vehicle a few days ago. We know that’s not the most common reason, but it’s still possible, especially if you are a chicken farmer!

After checking the cleanliness of your car, you still have to check a few systems. Rotten egg odors come from sulfur gasses in the vehicle that got vented from the engine bay (it can happen when you turn on the A/C unit).

1. Fuel System Failures

Fuel has hydrogen sulfide, a harmful component that smells like rotten eggs. The catalytic converter receives all the exhaust gasses, including hydrogen sulfide. This process allows the more toxic chemicals to turn into less harmful ones during normal combustion.
Hydrogen sulfide should be one of those chemicals. It should change to an odorless sulfur dioxide.

But when something interferes with this conversion process, the exhaust expels its gasses without the right combustion, and sometimes hydrogen sulfide goes in. Worse yet, these gasses may back up and go back into the engine bay, getting back into the cabin.

Two components of the fuel system can cause a rotten egg smell. Take your vehicle to a Phoenix auto repair shop if you see any damage to these components:

  • Pressure Sensors: Damaged fuel pressure sensors give the vehicle wrong indications for how much fuel the combustion chamber needs. The car can inject more fuel than needed, leading to unburned fuel going into the exhaust. This problematic failure can clog the cat, and may the hydrogen sulfide escape and cause the rotten egg smell.
  • Fuel Filter: Filters keep dirt and other external elements from entering the rest of the fuel system. If the filter clogs or fails it can cause the same issues as damaged pressure sensors. You should call a mechanic ASAP if you see a fuel leak in your vehicle that goes with a gasoline smell. Fuel leaks are extremely dangerous.

    2. Transmission Fluid Failures

    Transmission fluid can produce a smell similar to rotten eggs if left for too long without changes. A bad smell can also appear when the fluid leaks and burns the hot engine components.

    3. Faulty Car Battery

    Lead acid car batteries are formulated with sulfuric acid, a gas that’s popular for its peculiar smell. Check your battery to ensure it is not leaking so it does not damage other components in your car.

    Take your car to a Scottsdale auto repair shop if it has problems with the battery. Do not let it unattended as it could cause damage to your health.

    Some car batteries leak when there’s a mechanical defect, an internal electrical problem, or if they have been frozen or overcharged.

    Many drivers store their car batteries in the trunk or cabin (commonly under a seat). These batteries should be sealed or vented, if not, they could leak harmful gasses into the passenger compartment.

    You must fix the battery venting system as soon as you can to avoid more issues.

    4. Faulty Catalytic Converter

    As the name indicates, the catalytic converter is the component that converts smelly gasses into odorless ones, so you should check it out if your car smells bad. If this component is damaged or worn, it may not be working properly.

    It could also be clogged due to a combustion problem. Incomplete combustion sends unburnt fuel into the catalytic converter when it should not be there. The unburnt fuel can clog the internal honeycomb pattern affecting the catalyst’s job.

    When Should I Call a Professional?

    It’s very dangerous to touch or breathe hydrogen sulfide or sulfuric acid, so do not ignore your car’s bad smell. Go to a trusted auto repair shop to check the car and see why it’s smelling bad. Most of the time, you only need to replace a component.

    Scottsdale Muffler is ready to help you if you perceive a rotten egg smell in your car. We do everything from fixing and replacing engines and transmissions, to changing the oil, repairing the muffler, and tuning up your vehicle so it doesn’t need the more expensive repairs. Contact us now for more information!


    Published By: Chris McCurdy
    Scottsdale Muffler & Automotive
    1710 E Curry Rd
    Tempe, AZ 85281

    Office: 480-994-4741
    Website: https://scottsdalemuffler.com

    Office Hours:
    Monday: 8:00 a.m. – 5:00 p.m.
    Tuesday: 8:00 a.m. – 5:00 p.m.
    Wednesday: 8:00 a.m. – 5:00 p.m.
    Thursday: 8:00 a.m. – 5:00 p.m.
    Friday: 8:00 a.m. – 5:00 p.m.


    Posted: July 15, 2022