Sooo, I don't have any of the problems indicated below. Full power and acceleration, the smell comes from the air vents not the exhaust and no dark smoke. No O2 sensor codes yet, hmmm.

What problems a bad catalytic converter can cause in your BMW?

If you're noticing slow engine performance, reduced acceleration, a smell of sulfur or rotten eggs from the exhaust, dark exhaust smoke, or excessive heat from under the vehicle, they are symptoms of a clogged Catalytic Converter, and it needs to get repaired soon. Nov 30, 2022

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LEV
2011 X5 xDrive50 Black/black////M sport pack/all options
2006 ///M3 Cabrio Gone but not forgotten
2003.5 ///M3 Gone but not forgotten
2007 Aston Martin V8V Gone but not forgotten
2007 Porsche turbo Gone but not forgotten
1995 540i M-sport(1 of 70) Gone but not forgotten