900 SE Hatchback L4-1985cc 2.0L DOHC Turbo EFI (1997)
Catalytic Converter: All Technical Service Bulletins
Exhaust - Sulfur/Rotten Egg Smell
SI No. 100-0587
Date: April 2000
900, 9000, 9-3, 9-5
Complaint of Sulfur Smell from Exhaust
Customers may complain of a sulfur or "rotten egg" exhaust odor occurring during heavy acceleration, at Idle following sharp deceleration from cruising
speeds, backing up, or when exiting the car after switching the engine off.
All Saab Models
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 greatly to the "rotten egg" odor. The amount of sulfur content can vary between fuel brands, fuel grades and/or
from one geographic area to another.
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:
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.
Switch to a higher octane fuel. Premium grade fuel usually has lower sulfur content that regular grades of unleaded fuel. Again, it may take several
tanks of a higher octane grade before the odor decreases.
Replacing the TWC will not solve the odor complaint, is not recommended and is not covered under warranty for this complaint.