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Exhaust System - Excessive Sulfur Odors



TSB: 01-043/06


NOTE :This bulletin replaces 01-029/02. Please update your records accordingly.


This bulletin supersedes the previous bulletin 01-029/02, issued on 11/22/02. The APPLICABLE MODELS has been revised.


2000-2007 B-Series

2000-2003 Protege

2000-2005 Miata

2000-2002 626

2000-2002 Millenia

2000-2006 MPV

2001-2006 Tribute

2003-2007 Mazda6

2004-2007 Mazda3

2004-2007 RX-8

2006-2007 Mazda5

2006-2007 MX-5

2007 CX-7


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:

^ www.epa.gov