HVAC Rotten Egg Smell

[kerrton]

I have an 08 Rogue FWD, 35,000 km.

For the past several months, I get a strong rotten egg smell through my air vents ONLY after driving on the highway and coming to a complete stop, a couple seconds after stopping the smell kicks in. If I immediately run to the tailpipe and smell it, there is NO rotten egg smell, nothing out of the ordinary.

So I initially thought cat converter, but the exhaust smells and looks completely normal, AND this only happens under the very specific conditions I described, normal around-town driving and highway driving there's no problem, the air coming through the vents is nice and clean but the moment I stop after the highway it gets stinky in a hurry.

The fact that any gases are getting into my HVAC system and blowing in through the vents worries me, regardless of the source, I have a pregnant wife and a 2-year old so I'd like to get his figured out. Any ideas? At least a starting point of things to check? I talked to the dealer and they were very dismissive blaming it on the cabin filter or the fuel etc. but my cabin filter is brand new and the smell occured with 3 different fuel suppliers. Thanks in advance.

[kerrton]

I have also been able to replicate this by running the car in Park at around 3000 rpms with the fan on - within about 5 to 10 seconds the previously fresh air begins to smell of rotten eggs. I then quickly popped the hood and the smell completely fills the engine compartment as well, but the tailpipe emissions don't seem to be affected.

If it was the cat converter, that doesnt' explain why the smell is present in the engine compartment, and not really coming from the tailpipe, does it? Maybe exhaust leak?