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General :: Outside the Cube :: Auto :: Maintenance
Tips on maintenance of your vehicle.
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Generated 16:00:35 on Nov 16, 2019
My car's exhaust smells like rotten eggs
Question: My car's exhaus smells like rotten eggs when I start it up in the morning. Why is that?
Answer: On some vehicles, a sulfur smell or 'rotten egg' odor may be noticed coming from the exhaust system. The odor
is usually noticed after a cold start, fast idle, extended periods of idling and full throttle acceleration. Sulfur smell
is not an indication of an engine concern and will not cause reduced driveability or durability of the engine or
any of its emission components.
The sulfur smell or 'rotten egg' odor is caused by high amounts of sulfur in the gasoline being used in the vehicle.
Sulfur is normally eliminated during the refining process, but the EPA regulation of sulfur in gasoline differs
from state to state. Vehicles using fuel containing high amounts of sulfur will most likely emit sulfur smell from
the exhaust system.
When high sulfur fuel is burned, there is a chemical reaction in the catalytic converter causing the sulfur to oxidize.
As the vehicle is driven, the oxidizing reaction odor in the converter will decrease with mileage and age.
Replacing the catalytic converter will not eliminate sulfur smell and replacement will just extend the
period of time needed for the converter to 'age' allowing it to reduce sulfur smell to an acceptable
- Switch to a different brand of fuel and drive the vehicle for at least 100 miles. Monitor the decrease or
increase in sulfur smell.
- Do not add any type of 'fuel additive' as this could add sulfur to the fuel and cause/increase the odor.
- Try to avoid extended periods of short trip driving or aggressive acceleration.
- Request information from your local fuel dealers on the amounts of sulfur in their gasoline. Try to use fuel
containing the lowest amounts of sulfur.
- Visit the EPA and gasoline company websites to stay informed on any changes in fuel or environmental regulations.
A website to check is: EPA
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