S80 sounds like a popcorn popper throwing error codes p0422, p0432, & p0300.
 

I’m a first timer to this form so please be patient.
I have a 99 S80 non-turbo with 146k miles on it. The engine light has been coming on for about 3 minutes when cold and then it would go out. The car was running fine at the time. Last week it started to sound like a popcorn popper, with no codes showing up. This week, I received codes p0422, p0432, & p0300 and the car is running poorly, to say the least. When I hit the left catalytic converter, I can tell it’s clearly the source of my noise. Right side sounds solid.
I’m looking for some advice on what my options with question like; Since I have to replace at least one catalytic converter, how do I tell if the other one is working? Will I have any problems using an aftermarket converter? If yes, which ones are the best options? And, how do I tell if the O2 sensors are good?
Any help would be great.
Thanks, Dan

Take it to a Muffler shop..they can tell if your Catalytic converters are clogged up or not.

Do you smell any sulphur type odor..when you try to drive the car..? Are you having a problem climbing hills or accelerating..?

From what my code reader says..those codes are for the Catalytic converter...also they can get very HOT when they are going bad almost cherry red...I'd get it checked out.

No smell at at all. It didn't have any acceleration problems until the error codes came up, and now it is in like limp mode. No pickup at all.

It is possible the cat came apart and is restricting the exhaust.
One easy way to find out is to remove both front O2 sensors and drive the car. If it feels better the cat is clogged.

Thanks I will do that. Another question. Is anyone having problems with the after market cats. I found out that this car is from California and has two cats making it more expensive to fix with OEM parts. My question now would be, can I change it to a one cat system, or do I have to go with a two unit system?

this car will flip a bitch on codes if you switch the cat system, the ECM is only designed to recognize OEM emissions equipment sorry :(

EDIT: i'm sure not everything would throw it off (you'd hope) but you never know with these cars. hell i'm sure if you didn't have the right kind of aftermarket exhaust it'd get mad at you.

Thanks, Does anyone have any problems with the aftermarket Cats? The Dealer wants $2500 to replace and Midas wants $1500 for aftermarket cats.

Any help on this would be appreciated.

I have not messed with aftermarket ones.