Exhaust - Sulfur Smell

Category
Specifications

Section
0

Page
18

Issue
06/95-0587

Code
000

Subject
Complaint of Sulfur Smell from Exhaust

Application
900 and 9000 Models

Customers may complain of a sulfur or "rotten egg" exhaust odor occurring during heavy acceleration, at idle following sharp deceleration from cruising speeds, or when exiting the car after switching the engine off.

Cars Affected
900 and 9000 models.

Causes
Most of this odor is due to a tendency of all 3-way catalytic converters (TWC) - not just those in Saab cars - to store sulfur during steady-state conditions. The converter then releases the sulfur as hydrogen sulfide during fuel- rich engine running conditions such as idle after deceleration from cruising speeds or heavy acceleration.

Fuel is another factor that can contribute to the "rotten egg" odor. The amount of sulfur content can vary between fuel brands, fuel grades, or from one geographic area to another.

Action:

Please advise owners that the sulfur smell will usually lessen after the car is used for about 10,000 miles. If the customer's car has more than 10,000 miles or the customer wants to take more immediate action, the following recommendations may assist them in reducing the odor.

1. Switch to a different brand of fuel. Sulfur content may vary between brand names. Advise the customer that it may take several tanks of a different brand before the odor decreases.

2. Switch to a higher octane fuel. Premium grade fuel usually has a lower sulfur content than regular grades of unleaded fuel. Again, it may take several tanks of a higher octane grade before the odor decreases.

NOTE:
Replacing the TWC will not solve the odor complaint and is not recommended.