I had the same problem with my 95 LS400 with 112k. Local Toyota dealer got CODE P0420 (Bank One) - not sure if he's referring to his Bank Acct or location of problem :D
Quote for replacing the left cat was >$1300. As emissions test not required for cars older than 1996 in these parts, I'm dragging my feet about replacing the cat. CEL (Check light) remains on until it's replaced and other things might go wrong and I won't know it until the part totally fails, he tells me. Now, I want to believe that's all that is causing the CEL BUT as we have all heard "Trust but verify!".
So, what's to say it isn't my O2 sensors and not the cat.? I can get non-OEM EASTERN cats (made in PA) via car stuff for <$160 each and Bosch O2 sensors for ~$78 each so I'm not inclined to shell out OEM bucks for a 1995 car, as nice as it is.
If the O2 sensors were the cause of the CEL shouldn't they pop up with a code of their own? These are the original O2 sensors as best I can tell from all my repairs/maintenance records. What I hear from those in the know is that cats last but O2 sensors fail. If cats fail there is often something causing it. I use premium fuel from COSTCO (triple filtered but ???detergent levels) until recently when I just filled up with 87 octane (1st tank). I've learned that Top Tier fuels clean much better and I may decide to go for Shell or Texaco in the future.
Should I find a competent non-dealer mechanic to replace the O2 sensors since they are old?
Should I spring for the EASTERN catalytic converter and hope the CEL goes off thereafter?
Any advice is appreciated!
Ray
Followup on previous note:
I took it to an independent import repair shop. Diagnostic code confirmed P0420. After-market cat. with labor ~$600+ (vs >$1300 at Toyota/Non-Lexus dealer). So far so good. Hope it lasts and lasts.
