I just noticed this tonight while heading back from the restaurant. A rotten eggs/sulfur smell coming from either under the car or the exhaust. I'm going to check tomorrow in the daylight, but I did recently(three days ago) get my oil changed at Jiffy Lube using the Castrol Ultra synthetic 5/30. I also had them change out the fuel filter. They did put in some sort of fuel additive as well. So, I'm wondering if that could be it. Also, they put in that additive when I was at half a tank and now I'm at a quarter and noticing this smell. I've read posts saying it could possibly be a bad CAT, but I just wanted to get some opinions. The car seems to run as great as it always has and the idle is as smooth as ever. No temperature issues either. Oil pressure is solid as always. Anyhow, your thoughts are appreciated. Thanks......

 

Were you driving it hard? Clutch and/or cats give off a burnt rotten egg smell when subject to extreme heat.

 

You either got a bad tank of gas or your cats need to be replaced. Some fuel additives will destroy a Cat. We use to Own a gas station for many years we saw this a lot. Run another tank of gas and see.

 

I'm just gonna throw this out there...you say you were heading back from a restaurant. Were you or your wife/other just gassy and lettin' em rip?

 

Most additives nowadays are perfectly safe for converters. The fact that your gas was half full should not matter. When I had an older air cooled 911 my Porsche mechanic told me not to add gas to the 1/4 tank I had in the car (it was the powerful BG additive brand too). It caused no harm and worked well in 'cleaning' everything. Although it seems like a coincidence I suspect the cats are simply bad but I would also take Jazzman442's advice and run another full tank of gas through to make sure. Best of luck.

 

 

More than likely the rotten egg/sulfur smell came from the restaurant and lingered for awhile before it finally went away

But seriously, I'll just throw this out there anyhow.. So when was the last time you changed your cabin filter ? As a dirty filter just might be a possibility as well

 

You might try some catalytic converter cleaner. Add to gas.

 

That's an actual product?

 

You didn't happen to take up 2 parking spaces at the restaurant did you? Just sayin.

 

Yup. Check your local Auto Zone or Advance. They should have it .

 

Great I'll look for it. My DD has that smell and I was told it was the catalytic converters.