LS400_96

am getting a CEL for codes 420 and 430 on different occasions (Catalyst System Effieciency Below Threshold -- Bank 1 and Bank 2 respestively). In the service manual it says problem is either 3-way cat or O2 sensor. I have about 125,000 miles on my car and I dont think the previous owner ever changed any of these (checked and looks original).

I think the problem is the O2 sensors but am hearing LS400's 95 and up are having problems with catalytic converter. I have been getting this CEL for quite awhile and even passed a smog check a couple of months ago after clearing the CEL by taking the fuse out for EFI 1.

I have two questions to ask.

1) Have any of you guys changed your catalytic converters cuz they were not working for these years?
2) Do you guys think the catalytic converters need to be replaced or just the O2 sensors?

acf

Looks like additiude had a similar experience. I too have a 97 LS 400 so I called Lexus and they said the converters problem is very rare. Hope so. Good luck dude, let us know how you fare.

https://www.clublexus.com/forums/sho...threadid=90942