Yesterday I backed into the driveway and noticed a strong rotton egg smell when I backed up. Noticed this before too.
Set there and let it idle and it cleaned out and was fine.
No its not the 02 as the car is getting good mileage and only does this in reverse.
Could the PCM change the fuel enrichment only when backing up? Or am I picking up bad gas in the tank in reverse? Anyone else notice this on their car?

Rotten egg smell is usually caused by a bad catalytic converter. Also this wouldhappen when the car was warmed up.

you probably only smell it backing up because you are backing through your exhaust.

maybe it needs one of those converter cleaner additives.
Strange how there is no smell in the forward gears, even while idleing at a light.

It probably does do it, you just don't notice it. I agree with CC, it'* more noticable when you're backing up because you're driving through the exhaust fumes.

Maybe now is a good time to upgrade to a high flow cat? Get a Magnaflow.

I doubt the additive will do much for you. I don't put much faith in the "mechanic in a bottle" fixes....

May have figured this out.
The wife takes the car two days to work driving only two blocks.
I then take it cross town to Lowes for supplies and it burns all that rich fuel out of the cat from going short trips.

You need a pedal stompin long highway trip.. clean it out.