Sulfur Smell from my 2011 Chevrolet Impala

I purchased a 2011 Chevrolet Impala last year with 14,000. When the car reach 26,000 I begin to smell a very strong sulfur smell coming from the exhaust. I took the car to the local Chevrolet dealer and was told that the particles in the catalytic converter begin to break up at about 26,000 mile and the result
is a sulfur smell. I didn’t believe that all Impalas had this problem. So I took it to the Chevrolet dealer in the next town where I personally know and trust the maintenance chief. He put his two best men on the car and could not find anything wrong. I was told to try another gas station which I did but it did not help. I now have 31,000 miles on the car and the smell is very strong coming into the passenger compartment when stopped. Can you help?

John Gearheard

Sulfur smell from the exhaust has been a problem time to time across several brands.
I seem to see it (so to speak) coming from low mileage cars.
I think cat converters tend to make the smell less once they’re “broken in”.
If you’re getting good MPGs and no check engine light then it would be just a minor nuisance… However,

Getting the smell of your cars own exhaust in the passenger compartment could be a sign of a serious problem.
Is it coming in other than through an open window?

What you’re smelling is hydrogene sulfide. The catalytic converter is supposed to converter the hydrogene sulfide to sulfer dioxide which is odorless. If the engine isn’t running hot or there’s no excess fuel entering the engine such as from a leaking fuel pressure regulator, then the odor is caused from a defective catalytic converter.

If the dealer told you that the problem is with the catalytic converter, demand that they replace it under the 8 year/80,000 mile EPA mandated warranty.


I vote for fried battery.

Thank you all for your comments. I believe the exhaust is coming into the passenger compartment through the vents. Also, I will contact the dealer about replacing my catalytic converter.

The battery could indeed be the problem, as @Barkydog stated.

It could have a leaky case.

It could be overcharged from a faulty alternator/regulator

Chiming in on the battery possibility. Remember that car batteries are filled w/sulphuric acid. And H2S gas (rotten egg gas) can be emitted when something goes wrong with either the battery or the charging system. The rotten egg gas could easily get drawn into the air vents under the windshield and go directly into the passenger compartment. It’s not possible to tell without a visual inspection, and the cat remains a likely culprit, but OP should at least consider the battery as a potential cause. It will likely prove a lot less expensive to fix if it is the battery or charging system.