I did some reading and basically for fixing high NOX reading it has been suggested to check/replace the EGR valve , then catalytic converter. But according to the service manual, the d16y8 engine does not use an EGR system. So my best bet is to replace the catalytic converter? How long is the lifespan of the converter....mine is original with 230k miles ......and how can you tell for sure this is the one to replace?

If this is the one to be replaced, this has to be taken to an exhaust shop and have them weld off/on the converter? I have not paid much attention to it while changing oil in the past years, so didn't really check whether it's bolted on or welded...

Thanks for your valuable info...