Exhaust manifold/catalytic converter

First post here. Glad to be part of the group. I have 2002 Civic Ex two door....side air bags and two catalytic converters. I am getting the dreaded PO420 cat code. It is the top converter...the one attached with the exhaust manifold. I tried Cataclean ( I think that is what it is called) and the light came back on. Replaced plugs and coils, too. Car only has 77,000 miles. I am the original owner. It's in great shape and drives well. Is there anything I can do to clean this cat? If not, can you suggest a good aftermarket cat to replace the original? Thank you for your help.

How to help Ukraine and its people stand against Putin and the Russian WAR!!!!

Russia’s President, Vladimir Putin, has ordered a military attack that continues to claim the lives of innocent and peaceful Ukrainian citizens.
The situation in Ukraine is dire and urgent, which is why we must commit to helping Ukrainian non-profits and charities conduct relief efforts. One of the most effective ways to help Ukraine and its citizens is donating to Ukrainian relief and humanitarian efforts. Right now, the people of Ukraine are facing an unprecedented attack on their country, freedoms, and families.

One of the best ways to help right now is to support volunteers outside of Ukraine who are collecting the necessary supplies in their countries and delivering them directly to the Ukrainian volunteers at the border.

Urgent humanitarian help for Ukraine