Sulfur Smell or ‘Rotten Egg’ Odor from Exhaust – 1995-2016 Mazda

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1995-2009 B-Series 2001-2006 Tribute 2006-2015 Mazda5
1997-2003 Protege 2008-2011 Tribute 2007-2012 Mazda CX-7
1997-2005 Miata 2003-2016 Mazda6 2007-2016 Mazda CX-9
1997-2002 626 2004-2016 Mazda3 2011-2014 Mazda2
1997-2002 Millenia 2004-2011 Mazda RX-8 2013-2016 CX-5
1997-2006 MPV 2006-2016 Mazda MX-5 2016 CX-3


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.


CAUTION: 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 level.

  1. Switch to a different brand of fuel and drive the vehicle for at least 100 miles. Monitor the decrease or increase in sulfur smell.
  2. Do not add any type of ‘fuel additive’ as this could add sulfur to the fuel and cause/increase the odor.
  3. Try to avoid extended periods of short trip driving or aggressive acceleration.
  4. 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.
  5. Visit the EPA and gasoline company websites to stay informed on any changes in fuel or environmental regulations. A website to check is:


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