Vehicle is RX 330 05 model,car threw up CEL & VSC error light,code P0430 was seen on the scanner,i checked it out on Google, saw catalyst related articles, the tech guy has checked all O2 sensors, confirmed them ok,though the car seem to drive well but i think issues will come up later if not corrected,please what is the cost of catalyst, if there is any other thing to do please help.

read through the thread on how it was solved

https://www.nairaland.com/1487612/club-lexus/21

Had a similar issue,
Changed O2 sensor yet the codes came back and i was advised to drive the car that way. Fast forward after 2 years. I decided to replace my spark plugs with the oem replacement parts. Lo and behold, the codes left after that.

Good day, @ conyema12 this is intriguing, it might be a misfire from one of the cylinders that triggered the code,I saw a similar post on Google while trying to understand what am battling with though I saw lots of other issues that could throw up the code,I was confused and did not know where to start from. Where and how much did you buy the OEM spark plugs.

This is how I'd go about this problem:

NB: This problem is sometimes related to fuel system. Hence, my response.

1. How did he check the O2 Sensors? Did he use a DVM to check for continuity and resistance, the comparing that against a known reference?

If he did, and concluded the sensors are OK, then I'd have to look at the circuitry on the sensors, of there are any open. circuits linking to the ECU.

2. If that checks fine(circuits intact), I'd replace the spark plugs. Reason being that they reduced ability to provide spark as they age.

3.Cleaning of the O2S and the catalytic converters. I know guys here would say its a waste of time, and that won't work.

I have done this same procedure on an Acura MDX 2010. That fixed the issues.

As these components, spark plugs, catalytic converters, etc, age with time, carbon buildups gets entangled within them, causing this same problem.

4. I'd check for any intake air leaks in the engine compartment. Replace your air filter if its clogged.

5.Exhaust leaking through the neck, or the lines. Do you notice any high frequency noise from the car?
Ask your panel beater to have a look at the exhaust for signs leaks.

6. Lastly, of everything has being done, and still persist, I'd now conclude on the ECU. It could be that the ECU so t getting g enough voltage signals from the O2S.




Hope this provides you some of the info you may be graving for.





Regards,
Joseph
DW Nig Ltd
Isolo, Lagos
08066643532(WhatsApp/call).
www.dxta.net.ng