P0420 code on my Nissan

[NoorAutoExpert]

Hey everyone! I’m dealing with a P0420 code on my Nissan and I’m trying to understand the issue properly before spending money on unnecessary parts.

I’m looking for some **good, reliable online resources** that explain P0420 diagnosis and possible solutions in a straightforward way. Ideally, something that can help me figure out the most economical approach instead of just replacing the catalytic converter right away.

If you’ve used any useful websites, guides, or forums for this, I’d really appreciate the recommendations. Thanks!