Car Smells like rotten eggs when braking?

2022 HYUNDAI TUCSON
11,848 MILES • 2.5L • 4 CYL • 4WD • AUTOMATIC
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SHLOIMY
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Hi,

I'm driving long distances, I would say maybe an hour or more at the highway going regular fast speed and then afterwards i start to brake, my car starts to smell like rotten eggs. The more I brake the more it smells, interesting that local it doesn't happen. There's no engine light showing or anything....
Aug 2, 2023 at 9:13 AM
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JACOBANDNICKOLAS
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Hi,

Interestingly, a rotten egg smell is usually from the exhaust/catalytic converter. If you get out after this happens, can you tell if the smell is stronger at any of the wheels? If you leave the engine running, is the smell stronger near the exhaust?

Let me know that. Also, check around the wheels and exhaust under the vehicle to make sure nothing is stuck to a component such as a dead animal or plastic bag stuck to the exhaust.

Let me know.

joe
Aug 2, 2023 at 9:29 PM
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SHLOIMY
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Hi,

So, I tried to figure out what's wrong I checked all Over the car, but recently my car battery started to make issues it needed a boost. then like a few days ago it died fully. I wonder if the rotten egg smell is from the battery. I took the car to Hyundai dealership they changed the battery and said about the smell I need to change the cabin filter of the car. Wondering what you think?
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Aug 30, 2023 at 7:28 AM
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JACOBANDNICKOLAS
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Hi,

It could be that something got into the HVAC causing the odor, but on this new of vehicle, I would think the cabin air filter would still be good. Also, does it only happen when you use the brakes? If you allow the vehicle to be parked and idling, do you smell it?

Yes, a battery can cause it as well. It's interesting that the battery was drained on this new of vehicle.

If you want, here is a link that explains in general how to replace a cabin air filter. It wouldn't hurt to inspect it.

Also, once you stop the vehicle, do you still smell it, or does it go away? I still have a feeling it is related to the exhaust. Were they able to smell it when it was at the dealer? I ask because it is still 100% under warranty and if there is a noted problem, they are responsible for repairs.

Let me know.

Joe
Aug 30, 2023 at 7:30 PM
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SHLOIMY
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So, I didn't really focus exactly when I smelled it where and how long it smells but I did notice that it comes from the battery the smell....
Aug 30, 2023 at 7:35 PM
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JACOBANDNICKOLAS
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 110,190 POSTS
Hi,

This could indicate the battery is being over or under charged. Also, if there is a constant heavy load on the battery, that can cause the odor as well.

Do me a favor. Let's confirm the alternator is working properly. If you take a look at this link, it explains how to test the alternator. All you will need is a simple voltmeter or multimeter.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Let me know the results.

Take care,

Joe
Aug 30, 2023 at 8:18 PM