That "rotten egg" smell can come from a bad catalytic converter, which is pretty common in the Altimas per my master mechanic friend. I have a 2004 and have the same smell.
He told me it shouldn't need to be replaced until it throws a code in the computer (Service Engine light). And then it will cost about $700 to replace (with cheap labor from him).
I still have the smell a year later and it still hasn't thrown the code for the catalytic converter. Knock on wood.
Tuesday, October 12th, 2010 AT 1:24 PM