Are my O2 sensors bad? ( video of live data included )

[BoxsterInTheSun]

Happy Thursday Boxster experts!

I got the dreaded P0420 and P0430 codes on my new-to-me 2002 base 986 and I'm currently rushing to try and get it resolved so I can get it smogged here in California.

It's a long story that is documented here if you're interested.

I'm now at the point where I'm trying to figure out if the O2 sensors are the culprit. I captured a video of the live data from an ODBC scanner and would be super grateful if someone can interpret the out put and let me know if anything looks "off".

The video is here:

https://youtube.com/shorts/lD6E2Fj2JdE?si=84myzPnxX1jfHXbg

One other interesting thing that might be a clue here...

Typically this car "bogs down" a bit after a gear change and accelerating into the next gear, it's not horrendous, but definately noticable. However, when I clear the P0420 and P0430 codes, this "bog down" vanishes until the codes reappear. Seems odd and potentially a clue here?

Thank you as always, I appreciate this place a lot.

[JFP in PA]

P 0420 and 0430 indicate your maim cats are failing, not the O2 sensors. I would clear the codes, take the car for a run, and if the condition returns, you need new cats, which in CA have to be factory units.

[BoxsterInTheSun]

Originally Posted by JFP in PA

P 0420 and 0430 indicate your maim cats are failing, not the O2 sensors. I would clear the codes, take the car for a run, and if the condition returns, you need new cats, which in CA have to be factory units.

Thanks so much. 2 questions if the code returns:

1) Any sense in trying to clean the cats like I've seen done in various youtube videos?

2) Any thoughts on why this code causes the "bog down" issue I mentioned? And the minute I clear the codes that issue vanishes and it drives wonderfully?

Thanks again JFP, always appreciate your help and knowledge!

[JFP in PA]

One or probably both of the cats may be partially damaged, causing the DME to try to adjust the A/F ratio to compensate, causing the bog. We have never seen any of the cat bandaid fixes work.

If you want to confirm the cat condition, you need to take the car to an indpendent shop that has an exhaust "sniffer" system that analyzes the exhaust make up.

[BoxsterInTheSun]

Originally Posted by JFP in PA

One or probably both of the cats may be partially damaged, causing the DME to try to adjust the A/F ratio to compensate, causing the bog. We have never seen any of the cat bandaid fixes work.

If you want to confirm the cat condition, you need to take the car to an indpendent shop that has an exhaust "sniffer" system that analyzes the exhaust make up.

I removed all the O2 sensors this morning. The worst part of the job was the plastic clips that hold the plugs in place, took me FOREVER to unclip them!

The good news ( maybe it's good news? ) is that one of the sensors is visibly toast. The driver side post cat O2 sensor shown below. The others look ok, but I included pics of them anyway:





I did my best to get videos of the inside of the cataytic convertors.

Passenger side:

https://youtu.be/rG_matfnIzw?si=-mMnDU92WZaeKYoj

Driver side:

https://youtu.be/0Z_PGrSlLYE?si=xAeAo1G8y3zMNhq6


I can already tell I need to order at least 1 new post cat O2 sensor, I think it's a Bosch 15183 to replace the one that is obviously cooked.

Anything else jump out at you here JFP as a potential issue, or is starting with replacing that sensor a decent start?

THANK YOU again for all the help!