The car is a '01 Gs430 with 85k miles.

This is the second time in 6 months I've had the P0430 CEL light come on.
It comes back as "Catalyst System Efficiency Below Threshold Bank 2"

The first time it came on was in the dead of a very cold winter 6 months ago.
just last week it popped up again. This time in the heat of the summer.
Both times while cruising.

Has anyone experienced this code and understand what's going on ?
Is it possibly just a bad o2 sensor?

 

I had that code in FEB, I replaced the 02 sensor that plugs in at the passanger side floorboard..

I KEEL YOU!

 

i keel you?

 

Its a reference to Achmed's Avatar, Achmed the Dead Terrorist.

 

Who is he killing? the code or the OP lol

 

It could be the O2, a leak in your exhaust or your cat.

 

you guys are too funny.

Silence!

 

I'm going to throw parts at it and do what you did first after checking for exhaust leaks and connectors.

BCP43002; I'm hoping I don't have to deal with a dead cat at this time.

Thanks guys for the replies.

 

i doubt its your cat, check the o2 sensor by it, as well as the gaskets in front and behind the cat.

 

check o2 first.

its the cheaper of the many solutions

 

I have a 2000 gs400 with about 95k and last week my check engine indicator came on so I took it to the shop the mech tells me it's the cats the need to be replaced I said ok Ty and I took my car went for a second opinion and guy tells me the same at almost $800 formthe job I was upset I came on here to see how many other gs owners had the same problem quite a few after reading it could be an exhaust Leah I went over to willets point near citi field queens ny and had those hole in the wall muffler shops check it out guess what. Exhaust leak right on the flang between cat and exhaust pipe by post u2 sensor 30 he welded both sides shut and the light went off on it's own after about 20 miles thanks for the help guys

 

See, when you search, you win!

 

I had the same code recently and it turns out I had leaks at my flanges, but I also installed two new sensors which I ordered from amazon and so far no codes and my mileage is back to normal.

 

My 01 GS300 has the same code. I replaced all 4 oxygen sensor with brand new Denso parts and the code came back after driving about 65 miles. Will be checking for exhaust leaks tommorrow. Hope it is not the cat.

 

If you got no exhaust leaks and 4 new o2 sensors, the only thing left is the cat itself.