Camry flex pipe replaced and now I smell that "rotten egg" smell

Last week I had the flex pipe replaced on my 2003 Camry LE (128,000 miles). Now I’m smelling that “rotten egg” catalytic converter smell. Does this mean that the catalytic converter is bad and could it have been damaged during the repair? The smell started after the repair. Before I take it back to the shop, I’d like to have an idea what could have happened, if anything.

Thanks for your help!

How much have you driven the car?? Most new exsaust pipes have an oil on them (to prevent them from rusting while sitting around)… When this burns off it can smell for a few days… could this be your problem??

I don’t think this smell is from the oil. It’s a very distinct sulphur smell and I’ve smelled it several times since last week. The first time I smelled it, the car was in my driveway, so I know it came from my car and not someone else’s. I’ve driven about 300-400 miles since the flex pipe was changed and I smelled it again today.

What engine do you have?

The “rotton egg” smell that those of us around in the early '70s had to combat wasn’t actually from the cat converter. It’s actually from sulpher in the gasoline conbining with water molecules in the exhaust stream and forming sulpher hydroxide. When gasoline metering was turned toward “lean” to combat carbon monoxide and unburned hydrocarbons, there was more oxygen by volume in the stream for the hydrogen atoms to bond to (and less carbon to soak up the smelly stuff) and rotton eggs were common. The converter does nothing to contribute to the rotten egg smell…or to help it.

Chemists on the forum, I’ll be thrilled if you post and correct me. I’ll take it as an education. I believe the above is accurate, but add the disclaimer that I’m not a chemist.

OP: have you returned to the shop that installed it to discuss the new smell? That’s where you should start.

Yeah, if thats the case it could very well be the cat, but it could also be the fuel you used last. Even if you got it from the same gas station they could have gotten a bad batch or changed suppliers…

Could the shop have damaged the cat?? Ehh, kind of unlikley the factory ones are fairly resiliant… Besides dropping somthing into it that could have damaged it (what I have no idea), I cant really think of any way they shop could have damaged it… With that said If you do have to replace it, a factory one is a lot of $$$$. I would sugest having an universal one welded in. Much less money, and they do the job. Granted not as well as a factory one, but you can buy 9 or 10 universals for the price of one factory…

This article kind of explains what may be going on:

My advice change gas stations, run a few tanks thrugh (one will not do it) and see what happens

I’m inclined to suspect that it’s the oils from the manufacturing processes burnng off. Some of these oils are intentionally sulpher-rich, and residue can create a temporary rotton egg smell when it mixes with the water molecules in the exhaust. See the attached info on cutting oils

If I’m right they’ll burn off.

Thanks for the info, everyone. I’ll check with the shop and see what they have to say. Hopefully the smell will just go away with a few more miles.