My 2000 GS400 has about 115K miles on it and just started throwing this code. I had it checked at local garage and they said to replace CAT for $1700.00)

Most of the car's miles are highway but over the last 2 years I have been driving short trips. I have recently made a few 100mi + trips and the CEL goes off. No smell, car runs very strong and gets about 22-24 MPG on highway. I bought my own code reader since the local garages charge $90 just to check the code. I have read the many threads on this topic (O2 sensors, CATS, etc.) so appreciate anything further. Can you really get a quality CAT that you can trust anywhere but the dealership? I live in Northern Virgina and the dealerships look to charge you for breathing if they can. I don't want to spend thousands to then have the dealership or garage flunk the car's emissions. Lastly, will this code keep the car from passing emissions? - I get that when the CEL is on it will not pass, but how can I determine if it will flunk emissions due to actual exhaust output? Thanks.

 

First try changing the o2 sensors.

 

What kind of signal are you getting at the O2 sensors? A leaking exhaust system can show the same code as a deficient catalytic converter.

 

Like what GSteg said, check your exhaust system for leaks. I had the same P0430 CEL in my GS3. Unplugged battery at first for a temp fix, next day brought car to exhaust shop and found 3 small leaks, one in front, one in midpipe and one by the canister. I welded the front and midpipe solid but canister still leaks very small. Put about 150 miles or so into her and CEL has not popped back up*knock on wood*

 

Thanks. I will have the exhaust checked for leaks and let you know. Thanks again!

 

I had the same code on my 02 about 3 months ago. A good shop should be able to check your o2s. Have that done first, after that find you a good exhaust shop. They should be able to find a ODB2 cat that can replace the OEM cat. NOW here is the crappy thing, if you changed the one cat your probably going to have to change the other one too. I had one replaced and the system pulled a "pending" that later turned into "not efficent" so i had to replace both. Car runs great and no issues with aftermarket cats. and only cost 600 each as opposed to 3000.